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<!doctype HTML public "-//W3O//DTD W3 HTML 3.2//EN">
<HTML>
<HEAD>
<TITLE>The Fetchmail FAQ</TITLE>
<link rev=made href="mailto:esr@snark.thyrsus.com">
<meta name="description" content="Frequently asked questions about fetchmail.">
<meta name="keywords" content="fetchmail, POP, POP2, POP3, IMAP, remote mail">
</HEAD>
<BODY>
<table width="100%" cellpadding=0><tr>
<td width="30%">Back to <a href="index.html">Fetchmail Home Page</a>
<td width="30%" align=center>To <a href="/~esr/sitemap.html">Site Map</a>
<td width="30%" align=right>$Date: 2000/12/01 09:47:52 $
</table>
<HR>
<H1>Frequently Asked Questions About Fetchmail</H1>
Before reporting any bug, please read <a href="#G3">G3</a> for advice
on how to include diagnostic information that will get your bug fixed
as quickly as possible. <p>
If you have a question or answer you think ought to be added to this FAQ list,
mail it to fetchmail's maintainer, Eric S. Raymond, at
<A HREF="mailto:esr@thyrsus.com">esr@snark.thyrsus.com</A>.<p>
<h1>General questions:</h1>
<a href="#G1">G1. What is fetchmail and why should I bother?</a><br>
<a href="#G2">G2. Where do I find the latest FAQ and fetchmail sources?</a><br>
<a href="#G3">G3. I think I've found a bug. Will you fix it?</a><br>
<a href="#G4">G4. I have this idea for a neat feature. Will you add it?</a><br>
<a href="#G5">G5. Is there a mailing list for exchanging tips?</a><br>
<a href="#G6">G6. So, what's this I hear about a fetchmail paper?</a><br>
<a href="#G7">G7. What is the best server to use with fetchmail?</a><br>
<a href="#G8">G8. What is the best mail program to use with fetchmail?</a><br>
<a href="#G9">G9. How can I avoid sending my password en clair?</a><br>
<a href="#G10">G10. Is any special configuration needed to use a dynamic
IP address?</a><br>
<a href="#G11">G11. Is any special configuration needed to use firewalls?</a><br>
<a href="#G12">G12. Is any special configuration needed to <em>send</em> mail?</a><br>
<a href="#G13">G13. Is fetchmail Y2K-compliant?</a><br>
<a href="#G14">G14. Is there a way in fetchmail to support disconnected IMAP mode?</a><br>
<a href="#G15">G15. How will fetchmail perform under heavy loads?</a><br>
<h1>Build-time problems:</h1>
<a href="#B1">B1. Lex bombs out while building the fetchmail lexer.</a><br>
<a href="#B2">B2. I get link failures when I try to build fetchmail.</a><br>
<h1>Fetchmail configuration file grammar questions:</h1>
<a href="#F1">F1. Why does my old .fetchmailrc no longer work?</a><br>
<a href="#F2">F2. The .fetchmailrc parser won't accept my all-numeric user name.</a><br>
<a href="#F3">F3. The .fetchmailrc parser won't accept my host or username beginning with `no'.</a><br>
<a href="#F4">F4. I'm getting a `parse error' message I don't understand.</a><br>
<a href="#F5">F5. The %h and %p escapes aren't being interporated correctly.</a><br>
<h1>Configuration questions:</h1>
<a href="#C1">C1. Why do I need a .fetchmailrc when running as root on my own machine?</a><br>
<a href="#C2">C2. How can I arrange for a fetchmail daemon to get killed when I log out?</a><br>
<a href="#C3">C3. How do I know what interface and address to use with --interface?</a><br>
<a href="#C4">C4. How can I set up support for sendmail's anti-spam features?</a><br>
<a href="#C5">C5. How can I poll some of my mailboxes more/less often than others?</a><br>
<a href="#C6">C6. Fetchmail works OK started up manually, but not from an init script.</a><br>
<a href="#C7">C7. How can I forward mail to another host?.</a><br>
<h1>How to make fetchmail play nice with various MTAs:</h1>
<a href="#T1">T1. How can I use fetchmail with sendmail?</a><br>
<a href="#T2">T2. How can I use fetchmail with qmail?</a><br>
<a href="#T3">T3. How can I use fetchmail with exim?</a><br>
<a href="#T4">T4. How can I use fetchmail with smail?</a><br>
<a href="#T5">T5. How can I use fetchmail with SCO's MMDF?</a><br>
<a href="#T6">T6. How can I use fetchmail with Lotus Notes?</a><br>
<h1>How to make fetchmail work with various servers:</h1>
<a href="#S1">S1. How can I use fetchmail with qpopper?</a><br>
<a href="#S2">S2. How can I use fetchmail with Microsoft Exchange?</a><br>
<a href="#S3">S3. How can I use fetchmail with Compuserve RPA?</a><br>
<a href="#S4">S4. How can I use fetchmail with Demon Internet's SDPS?</a><br>
<a href="#S5">S5. How can I use fetchmail with usa.net's servers?</a><br>
<a href="#S6">S6. How can I use fetchmail with HP OpenMail?</a><br>
<a href="#S7">S7. How can I use fetchmail with geocities POP3 servers?</a><br>
<a href="#S8">S8. How can I use fetchmail with Hotmail?</a><br>
<a href="#S9">S9. How can I use fetchmail with MSN?</a><br>
<a href="#S10">S10. How can I use fetchmail with SpryNet?</a><br>
<a href="#S11">S11. How can I use fetchmail with FTGate?</a><br>
<a href="#S12">S12. How can I use fetchmail with MailMax?</a><br>
<a href="#S13">S13. How can I use fetchmail with Novell GroupWise?</a><br>
<a href="#S14">S14. How can I use fetchmail with InterChange?</a><br>
<h1>How to set up well-known security and authentication methods:</h1>
<a href="#K1">K1. How can I use fetchmail with SOCKS?</a><br>
<a href="#K2">K2. How can I use fetchmail with IPv6 and IPsec?</a><br>
<a href="#K3">K3. How can I get fetchmail to work with ssh?</a><br>
<a href="#K4">K4. What do I have to do to use the IMAP-GSS protocol?</a><br>
<a href="#K5">K5. How can I use fetchmail with SSL?</a><br>
<h1>Runtime fatal errors:</h1>
<a href="#R1">R1. Fetchmail isn't working, and -v shows `SMTP connect failed' messages.</a><br>
<a href="#R2">R2. When I try to configure an MDA, fetchmail doesn't work.</a><br>
<a href="#R3">R3. Fetchmail dumps core when given an invalid rc file.</a><br>
<a href="#R4">R4. Fetchmail dumps core in -V mode, but operates normally otherwise.</a><br>
<a href="#R5">R5. Running fetchmail in daemon mode doesn't work.</a><br>
<a href="#R6">R6. Fetchmail hangs when used with pppd.</a><br>
<a href="#R7">R7. Fetchmail randomly dies with socket errors.</a><br>
<a href="#R8">R8. Fetchmail running as root stopped working after an OS upgrade</a><br>
<a href="#R9">R9. Fetchmail is timing out after fetching certain
messages but before deleting them</a><br>
<a href="#R10">R10. Fetchmail is timing out during message fetches</a><br>
<h1>Disappearing mail</h1>
<a href="#D1">D1. I think I've set up fetchmail correctly, but I'm not getting any mail.</a><br>
<a href="#D2">D2. All my mail seems to disappear after a dropped connection.</a><br>
<a href="#D3">D3. Mail that was being fetched when I interrupted my fetchmail seems to have been vanished.</a><br>
<h1>Multidrop-mode problems:</h1>
<a href="#M1">M1. I've declared local names, but all my multidrop mail is going to root anyway.</a><br>
<a href="#M2">M2. I can't seem to get fetchmail to route to a local domain properly.</a><br>
<a href="#M3">M3. I tried to run a mailing list using multidrop, and I have a mail loop!</a><br>
<a href="#M4">M4. My multidrop fetchmail seems to be having DNS problems.</a><br>
<a href="#M5">M5. I'm seeing long DNS delays before each message is processed.</a><br>
<a href="#M6">M6. How do I get multidrop mode to work with majordomo?</a><br>
<a href="#M7">M7. Multidrop mode isn't parsing envelope addresses from
my Received headers as it should.</a><br>
<a href="#M8">M8. Users are getting multiple copies of messages.</a><br>
<h1>Mangled mail:</h1>
<a href="#X1">X1. Spurious blank lines are appearing in the headers of fetched mail.</a><br>
<a href="#X2">X2. My mail client can't see a Subject line.</a><br>
<a href="#X3">X3. Messages containing "From" at start of line are being split.</a><br>
<a href="#X4">X4. My mail is being mangled in a new and different way.</a><br>
<a href="#X5">X5. Using POP3, retrievals seems to be fetching too much!</a><br>
<a href="#X6">X6. My mail attachments are being dropped or mangled.</a><br>
<a href="#X7">X7. Some mail attachments are hanging fetchmail.</a><br>
<h1>Other problems:</h1>
<a href="#O1">O1. The --logfile option doesn't work if the logfile doesn't exist.</a><br>
<a href="#O2">O2. Every time I get a POP or IMAP message the header is
dumped to all my terminal sessions.</a><br>
<a href="#O3">O3. Does fetchmail reread its rc file every poll cycle?</a><br>
<a href="#O4">O4. Why do deleted messages show up again when I take
a line hit while downloading?</a><br>
<a href="#O5">O5. Why is fetched mail being logged with my name, not the real From address?</a><br>
<a href="#O6">O6. I'm seeing long sendmail delays or hangs near the start of each poll cycle.</a><br>
<a href="#O7">O7. Why doesn't fetchmail deliver mail in date-sorted order?</a><br>
<a href="#O8">O8. I'm using pppd. Why isn't my monitor option working?</a><br>
<a href="#O9">O9. Why does fetchmail keep retrieving the same messages
over and over?</a><br>
<h1>Answers:</h1>
<hr>
<h2><a name="G1">G1. What is fetchmail and why should I bother?</a></h2>
Fetchmail is a one-stop solution to the remote mail retrieval problem
for Unix machines, quite useful to anyone with an intermittent PPP or
SLIP connection to a remote mailserver. It can collect mail using any
variant of POP or IMAP and forwards via port 25 to the local SMTP
listener, enabling all the normal forwarding/filtering/aliasing
mechanisms that would apply to local mail or mail arriving via a
full-time TCP/IP connection.<p>
Fetchmail is not a toy or a coder's learning exercise, but an
industrial-strength tool capable of transparently handling every
retrieval demand from those of a simple single-user ISP connection up
to mail retrieval and rerouting for an entire client domain.
Fetchmail is easy to configure, unobtrusive in operation, powerful,
feature-rich, and well documented. <P>
Fetchmail is <a href="http://www.opensource.org">open-source</a>
software. The openness of the sources is the strongest assurance of
quality you can have. Extensive peer review by a large,
multi-platform user community has shown that fetchmail is as near
bulletproof as the underlying protocols permit.<p>
Fetchmail is licensed under the <a
href="http://gnu.org//copyleft/gpl.html">GNU General Public
License</a>.<p>
If you found this FAQ in the distribution, see the README for fetchmail's
full feature list.<p>
<hr>
<h2><a name="G2">G2. Where do I find the latest FAQ and fetchmail
sources?</a></h2>
The latest HTML FAQ is available alongside the latest fetchmail
sources at the fetchmail home page:
<a href="http://www.tuxedo.org/~esr/fetchmail">
http://www.tuxedo.org/~esr/fetchmail</a>. You can also usually find
both in the <a
href="http://sunsite.unc.edu/pub/Linux/system/mail/pop/!INDEX.html">POP
mail tools directory on Sunsite</a>.<p>
A text dump of this FAQ is included in the fetchmail
distribution. Because it freezes at distribution release time, it may
not be completely current.<p>
<hr>
<h2><a name="G3">G3. I think I've found a bug. Will you fix it?</a></h2>
Yes I will, provided you include enough diagnostic information for me
to go on. Send bugs to <a
href="mailto:fetchmail-friends@ccil.org">fetchmail-friends</a>. When reporting
bugs, please include the following:
<ol>
<li>Your operating system.
<li>Your compiler version, if you built from source; otherwise, the
name and origin ogf the RPM or other binary package you installed.
<li>A copy of your POP or IMAP server's greeting line.
<li>The name and version of the SMTP listener or MDA you are forwarding to.
<li>Any command-line options you used.
<li>The output of fetchmail -V called with whatever other
command-line options you used.
</ol>
If you have FTP access to your remote mail account, and you have any
suspicion that the bug was triggered by a particular message, please
include a copy of the message that triggered the bug.<p>
Often, the first thing I will do when you report a bug is tell you to
upgrade to the newest version of fetchmail, and then see if the
problem reproduces. So you'll probably save us both time if you
upgrade and test with the latest version <em>before</em> sending in a
bug report.<P>
Another useful thing you can do, if you're using POP3, is to test for
IMAP4 support on your mailserver using the autoprobe function of
fetchmailconf. If you have IMAP4, and fetchmailconf doesn't tell you
it's broken, switch immediately. POP3 is a weak, poorly-designed
protocol with chronic problems, and the later versions after RFC1725
actually get worse rather than better. Changing over to IMAP4 may well
make your problem go away -- and if your ISP doesn't have IMAP4
support, bug them to supply it.<p>
It is helpful if you include your .fetchmailrc file, but not necessary
unless your symptom seems to involve an error in configuration
parsing. If you do send in your .fetchmailrc, mask the passwords
first! <p>
If fetchmail seems to run and fetch mail, but the headers look mangled
(that is, headers are missing or blank lines are inserted in the
headers) then read the FAQ items in section <a href="#X1">X</a>
before submitting a bug report. Pay special attention to the item on
<a href="#generic_mangling">diagnosing mail mangling</a>. There are
lots of ways for other programs in the mail chain to screw up that
look like fetchmail's fault, but you may be able to fix these by
tweaking your configuration.<P>
A transcript of the failed session with -v -v (yes, that's
<em>two</em> -v options, enabling debug mode) will almost always be useful.
It is very important that the transcript include your POP/IMAP server's
greeting line, so I can identify it in case of server problems. This
transcript will not reveal your passwords, which are specially masked
out precisely so the transcript can be passed around.<P>
If the bug involves a core dump or hang, a gdb stack trace is good to have.
(Bear in mind that you can attach gdb to a running but hung process by
giving the process ID as a second argument.) You will need to
reconfigure with <p>
<PRE>
CFLAGS=-g LDFLAGS=" " ./configure
</PRE>
and then rebuild in order to generate a version that can be gdb-traced.<p>
Best of all is a mail file which, when fetched, will reproduce the
bug under the latest (current) version.<p>
Any bug I can reproduce will usually get fixed very quickly, often
within 48 hours. Bugs I can't reproduce are a crapshoot. If the
solution isn't obvious when I first look, it may evade me for a long
time (or to put it another way, fetchmail is well enough tested that the
easy bugs have long since been found). So if you want your bug fixed
rapidly, it is not just sufficient but nearly <em>necessary</em> that
you give me a way to reproduce it.<p>
<hr>
<h2><a name="G4">G4. I have this idea for a neat feature. Will you add it?</a></h2>
Probably not. Most of the feature suggestions I get are for ways to
set various kinds of administrative policy or add more spam filtering
(the most common one, which I used to get about four million times a week
and got <em>really</em> tired of, is for tin-like kill files).<p>
You can do spam filtering better with procmail or maildrop on the
server side and (if you're the server sysadmin) sendmail.cf domain
exclusions. You can do other policy things better with the
<CODE>mda</CODE> option and script wrappers around fetchmail. If
it's a prime-time-vs.-non-prime-time issue, ask yourself whether a
wrapper script called from crontab would do the job.<p>
I'm not going to do these; fetchmail's job is transport, not policy, and I
refuse to change it from doing one thing well to attempting many things badly.
One of my objectives is to keep fetchmail simple so it stays reliable.<p>
For reasons fetchmail doesn't have other commonly-requested features
(such as password encryption, or multiple concurrent polls from the
same instance of fetchmail) see the <a
href="http://www.tuxedo.org/~esr/fetchmail/design-notes.html">design notes</a>.<p>
Fetchmail is a mature project, no longer in constant active
development. It is no longer my top project, and I am going to be
quite reluctant to add features that might either jeopardize its
stability or involve me in large amounts of coding.<p>
All that said, if you have a feature idea that really is about a transport
problem that can't be handled anywhere but fetchmail, lay it on me. I'm
very accommodating about good ideas.<p>
<hr>
<h2><a name="G5">G5. Is there a mailing list for exchanging tips?</a></h2>
There is a fetchmail-friends list for people who want to discuss fixes
and improvements in fetchmail and help co-develop it. It's at <a
href="mailto:fetchmail-friends@thyrsus.com">fetchmail-friends@thyrsus.com</a>.
There is also an announcements-only list, <em>fetchmail-announce@thyrsus.com</em>.<P>
Both lists are SmartList reflectors; sign up in the usual way with a
message containing the word "subscribe" in the subject line sent to
<a href="mailto:fetchmail-friends-request@thyrsus.com?subject=subscribe">
fetchmail-friends-request@thyrsus.com</a> or
<a href="mailto:fetchmail-announce-request@thyrsus.com?subject=subscribe">
fetchmail-announce-request@thyrsus.com</a>. (Similarly, "unsubscribe"
in the Subject line unsubscribes you, and "help" returns general list help) <p>
<hr>
<h2><a name="G6">G6. So, what's this I hear about a fetchmail paper?</a></h2>
The fetchmail development was also a sociological experiment, an
extended test to see if my theory about the critical features of the
Linux development model is correct.<p>
The experiment was a success. I wrote a paper about it titled <a
href="http://www.tuxedo.org/~esr/writings/cathedral.html">The
Cathedral and the Bazaar</a> which was first presented at Linux
Kongress '97 in Bavaria and very well received there. It was also
given at Atlanta Linux Expo, Linux Pro '97 in Warsaw, and the first
Perl Conference, at UniForum '98, and was the basis of an invited
presentation at Usenix '98. The folks at Netscape tell me it helped
them decide to <a
href="http://www.netscape.com/newsref/pr/newsrelease558.html"> give
away the source for Netscape Communicator</a>.<p>
If you're reading a non-HTML dump of this FAQ, you can find the paper
on the Web with a search for that title.<p>
<hr>
<h2><a name="G7">G7. What is the best server to use with fetchmail?</a></h2>
The short answer: IMAP4rev1 running over Unix.<P>
Here's a longer answer: <P>
Fetchmail will work with any POP, IMAP, or ESMTP/ETRN server that
conforms to the relevant RFCs (and even some outright broken ones like
<a href="#S2">Microsoft Exchange</a> and <a href="#S12">Novell
GroupWise</a>). This doesn't mean it works equally well with all,
however. POP2 servers, and POP3 servers without LAST, limit
fetchmail's capabilities in various ways described on the manual
page.<P>
Most modern Unixes (and effectively all Linux/*BSD systems) come with
POP3 support preconfigured (but beware of the horribly broken POP3
server mentioned in <a href="#D2">D2</a>). An increasing minority
also feature IMAP (you can detect IMAP support by running fetchmail in
AUTO mode, or by using the `Probe for supported protocols' function in
the fetchmailconf utility).<P>
If you have the option, we recommend using or installing an IMAP4rev1
server; it has the best facilities for tracking message `seen' states.
It also recovers from interrupted connections more gracefully than
POP3, and enables some significant performance optimizations.<P>
Don't be fooled by NT/Exchange propaganda. M$ Exchange is just plain
broken (see item <a href="#S2">S2</a>) and NT cannot handle the
sustained load of a high-volume remote mail server. Even Microsoft
itself knows better than to try this; their own Hotmail service runs
over Solaris! For extended discussion, see John Kirch's excellent <a
href="http://unix-vs-nt.org/kirch/">white paper</a> on Unix
vs. NT performance.<P>
You can find sources for IMAP software at <a
href="http://www.imap.org">The IMAP Connection</a>; we like the
open-source <a href="ftp://ftp.cac.washington.edu/imap/">UW IMAP</a>
server, which is the reference implementation of IMAP. UW IMAP's
support for GSSAPI gives you a good way to authenticate without
sending a password en clair.<P>
Source for a high-quality supported implementation of POP is available
from the <a href="ftp://ftp.qualcomm.com/eudora/servers/unix/popper/">Eudora
FTP site</a>. Don't use 2.5, which has a rather restrictive license.
The 2.5.2 version appears to restore the open-source license of
previous versions.<P>
<hr>
<h2><a name="G8">G8. What is the best mail program to use with fetchmail?</a></h2>
Fetchmail will work with all popular <a href="#T1">mail transport programs</a>.
It also doesn't care which user agent you use, and user agents are as a
rule almost equally indifferent to how mail is delivered into your system
mailbox. So any of the popular Unix mail agents --
<a href="http://www.myxa.com/old/elm.html">elm</a>,
<a href="http://www.washington.edu/pine/">pine</a>
<a href="http://www.cs.indiana.edu/docproject/mail/mh.html">mh</a>,
or <a href="http://www.mutt.org">mutt</a>
-- will work fine with fetchmail.<p>
All this having been said, I can't resist putting in a discreet plug
for <a href="http://www.mutt.org">mutt</a>. My own personal mail
setup is sendmail plus fetchmail plus mutt. Mutt's interface is only
a little different from that of its now-moribund ancestor elm, but its
excellent handling of MIME and PGP put it in a class by itself. You
won't need its built-in POP3 support, though; most of the mutt
developers will cheerfully admit that fetchmail's is better :-).<p>
<hr>
<h2><a name="G9">G9. How can I avoid sending my password en clair?</a></h2>
Depending on what your mail server you are talking to, this ranges
from trivial to impossible. It may even be next to useless.<P>
Most people use fetchmail over phone wires, which are hard to tap.
Anybody with the skill and resources to do this could get into your
server mailbox with much less effort by subverting the server host.
So if your provider setup is modem wires going straight into a service
box, you probably don't need to worry.<P>
In general there is little point in trying to secure your fetchmail
transaction unless you trust the security of the server host you are
retrieving mail from. Your vulnerability is more likely to be an
insecure local network on the server end (e.g. to somebody with a TCP/IP
packet sniffer intercepting Ethernet traffic between the modem
concentrator you dial in to and the mailserver host).<P>
Having realized this, you need to ask whether password encryption
alone will really address your security exposure. If you think you
might be snooped between server and client, it's better to use
end-to-end encryption on your whole mail stream so none of it can be
read. One of the advantages of fetchmail over conventional SMTP-push
delivery is that you may be able to arrange this by using ssh(1); see
<a href="#K3">K3</a>.<P>
Note that ssh is not a complete privacy solution either, as your mail
could have been snooped in transit to your POP server from wherever it
originated. For best security, agree with your correspondents to use
a tool such as <a href="http://www.gnupg.org/">GPG</a> (Gnu Privacy
Guard) or PGP (Pretty Good Privacy).<P>
If ssh/sshd isn't available, or you find it too complicated for you to
set up, password encryption will at least keep a malicious cracker
from deleting your mail, and require him to either tap your connection
continuously or crack root on the server in order to read it.<P>
You can deduce what encryptions your mail server has available
by looking at the server greeting line (and, for IMAP, the
response to a CAPABILITY query). Do a <code>fetchmail -v</code>
to see these, or telnet direct to the server port (110 for POP3, 143 for
IMAP).<P>
The facility you are most likely to have available is APOP. This is a
POP3 feature supported by many servers (fetchmailconf's autoprobe
facility will detect it and tell you if you have it). If you see
something in the greeting line that looks like an
angle-bracket-enclosed Internet address with a numeric left-hand part,
that's an APOP challenge (it will vary each time you log in). You can
register a secret on the host (using <code>popauth(8)</code> or some
program like it). Specify the secret as your password in your
.fetchmailrc; it will be used to encrypt the current challenge, and
the encrypted form will be sent back the the server for
verification.<P>
Alternatively, you may have Kerberos available. This may require you
to set up some magic files in your home directory on your client
machine, but means you can omit specifying any password at all.<P>
Fetchmail supports two different Kerberos schemes. One is a
POP3 variant called KPOP; consult the documentation of your mail
server to see if you have it (one clue is the string "krb-IV" in the
greeting line on port 110). The other is an IMAP facility described
by RFC1731. You can tell if this one is present by looking for
AUTH=KERBEROS_V4 in the CAPABILITY response.<P>
If you are fetching mail from a CompuServe POP3 account, you can use
their RPA authentication (which works much like APOP). See <a
href="#S3">S3</a> for details. If you are fetching mail from
Microsoft Exchange, you will be able to use NTLM.<P>
Your POP3 server may have the RFC1938 OTP capability to use one-time
passwords (if it doesn't, you can get OTP patches for the 2.2 version
of the Qualcomm popper from <a href="#cmetz">Craig Metz</a>). To check
this, look for the string "otp-" in the greeting line. If you see it,
and your fetchmail was built with OPIE support compiled in (see the
distribution INSTALL file), fetchmail will detect it also. When using
OTP, you will specify a password but it will not be sent en clair.<P>
Sadly, there is at present (September 1999) no OTP or APOP-like
facility generally available on IMAP servers. However, there do exist
patches which will OTP-enable the University of Washington IMAP
daemon, version 4.2-FINAL. We have a report that the GSSAPI support
in fetchmail works with the GSSAPI support in the most recent version
of UW IMAP. Or you can use <a href="#K5">SSL</a> for complete
end-to-end encryption if you have an SSL-enabled mailserver.<P>
You can get both POP3 and IMAP OTP patches from <a name="cmetz">Craig
Metz</A> at <a
href="http://www.inner.net/pub/">http://www.inner.net/pub/</a>.<P>
These patches use a SASL authentication method named "X-OTP" because
there is not currently a standard way to do this; fetchmail also uses
this method, so the two will interoperate happily. They better,
because this is how Craig gets his mail ;-)<P>
<hr>
<h2><a name="G10">G10. Is any special configuration needed to use a dynamic IP address?</a></h2>
Yes. In order to avoid giving indigestion to certain picky MTAs
(notably <a href="#T3">exim</a>), fetchmail always makes the RCPT TO
address it feeds the MTA a fully qualified one with a hostname part.
Normally it does this by appending @ and "localhost", but when you are
using Kerberos or ETRN mode it will append @ and your machine's
fully-qualified domain name (FQDN).<P>
Appending the FQDN can create problems when fetchmail is running in daemon
mode and outlasts the dynamic IP address assignment your client
machine had when it started up.<P>
Since the new IP address (looked up at RCPT TO interpretation time)
doesn't match the original, the most benign possible result is that
your MTA thinks it's seeing a relaying attempt and refuses. More
frequently, fetchmail will try to connect to a nonexistent host
address and time out. Worst case, you could up forwarding your mail
to the wrong machine!<P>
Use the <code>smtpaddress</code> option to force the appended hostname
to one with a (fixed) IP address of 127.0.0.1 in your
<code>/etc/hosts</code>. (The name `localhost' will usually work; or
you can use the IP address itself).<P>
Only one fetchmail option interacts directly with your IP address,
`<code>interface</code>'. This option can be used to set the gateway
device and restrict the IP address range fetchmail will use. Such a
restriction is sometimes useful for security reasons, especially on
multihomed sites. See <a href="#C3">C3</a>.<P>
I recommend against trying to set up the <code>interface</code> option
when initially developing your poll configuration -- it's never
necessary to do this just to get a link working. Get the link working
first, observe the actual address range you see on connections, and
add an <code>interface</code> option (if you need one) later.<P>
You can't use ETRN if you have a dynamic IP address (your ISP changes
your IP address occasionally, possibly with every connect). You need
to have your own registered domain and a definite IP address
registered for that domain. The server needs to be configured to
accept mail for your domain but then queue it to forward to your
machine. ETRN just tells to server to flush its queue for your
domain. Fetchmail doesn't actually get the mail in that case.<p>
If you're using a dynamic-IP configuration, one other (non-fetchmail)
problem you may run into with outgoing mail is that some sites will
bounce your email because the hostname your giving them isn't real
(and doesn't match what they get doing a reverse DNS on your
dynamically-assigned IP address). If this happens, you need to hack
your sendmail so it masquerades as your host. Setting<P>
<pre>
DMsmarthost.here
</pre>
in your <code>sendmail.cf</code> will work, or you can set<P>
<pre>
MASQUERADE_AS(smarthost.here)
</pre>
in the m4 configuration and do a reconfigure. (In both cases, replace
<code>smarthost.here</code> with the actual name of your mailhost.)
See the <a href="http://www.lege.com/sendmail-FAQ.txt">sendmail
FAQ</a> for more details.<P>
<hr>
<h2><a name="G11">G11. Is any special configuration needed to use firewalls?</a></h2>
No. You can use fetchmail with SOCKS, the standard tool for
indirecting TCP/IP through a firewall. You can find out about SOCKS,
and download the SOCKS software including server and client code, at
the <a href="http://www.socks.nec.com/">SOCKS distribution
site</a>.<P>
The specific recipe for using fetchmail with a firewall is at <a
href="#K1">K1</a><P>
<hr>
<h2><a name="G12">G12. Is any special configuration needed to <em>send</em> mail?</a></h2>
A user asks: but how do we send mail out to the POP3 server? Do I need
to implement another tool or will fetchmail do this too?<p>
Fetchmail only handles the receiving side. The sendmail or other
preinstalled MTA on your client machine will handle sending mail
automatically; it will ship mail that is submitted while the
connection is active, and put mail that is submitted while
the connection is inactive into the outgoing queue.<P>
Normally, sendmail is also run periodically (every 15 minutes on most
Linux systems) in a mode that tries to ship all the mail in the
outgoing queue. If you have set up something like pppd to
automatically dial out when your kernel is called to open a TCP/IP
connection, this will ensure that the mail gets out.<P>
<hr>
<h2><a name="G13">G13. Is fetchmail Y2K-compliant?</a></h2>
Fetchmail is fully Y2K-compliant.<P>
Fetchmail could theoretically have problems when the 32-bit time_t
counters roll over in 2038, but I doubt it. Timestamps aren't used
for anything but log entry generation. Anyway, if you aren't running
on a 64-bit machine by then, you'll deserve to lose.<P>
<hr>
<h2><a name="G14">G14. Is there a way in fetchmail to support disconnected IMAP mode?</a></H2>
No. Fetchmail is a mail transport agent, best understood as a protocol
gateway between POP3/IMAP servers and SMTP. Disconnected operation
requires an elaborate interactive client. It's a very different problem.<p>
<hr>
<h2><a name="G15">G15. How will fetchmail perform under heavy loads?</a></h2>
Fetchmail streams message bodies line-by-line; the most core it
ever requires per message is enough memory to hold the RFC822 header, and
that storage is freed when body processing begins. It is, accordingly,
quite economical in its use of memory.<p>
After startup time, a fetchmail running in daemon mode stats its
configuration file once per poll cycle to see whether it has changed
and should be rescanned. Other than that, a fetchmail in normal
operation doesn't touch the disk at all; that job is left up to the
MTA or MDA the fetchmail talks to.<p>
Fetchmail's performance is usually bottlenecked by latency on the POP
server or (less often) on the TCP/IP link to the server. This is not
a problem readily solved by tuning fetchmail, or even by buying more
TCP/IP capacity (which tends to improve bandwidth but not necessarily
latency).<p>
<hr>
<h2><a name="B1">B1. Lex bombs out while building the fetchmail lexer.</a></h2>
In the immortal words of Alan Cox the last time this came up: ``Take
the Solaris lex and stick it up the backside of a passing Sun
salesman, then install <a
href="ftp://ftp.gnu.org/pub/non-gnu/flex/">flex</a> and use that. All
will be happier.''<P>
I couldn't have put it better myself, and ain't going to try now.<P>
(The same problem has been reported under HP-UX v10.20 and IRIX)<P>
<hr>
<h2><a name="B2">B2. I get link failures when I try to build fetchmail.</a></h2>
If you get errors resembling these<P>
<pre>
mxget.o(.text+0x35): undefined referenceto `__res_search'
mxget.o(.text+0x99): undefined reference to`__dn_skipname'
mxget.o(.text+0x11c): undefined reference to`__dn_expand'
mxget.o(.text+0x187): undefined reference to`__dn_expand'
make: *** [fetchmail] Error 1
</pre>
then you must add "-lresolv" to the LOADLIBS line in your Makefile
once you have installed the `bind' package.<P>
<hr>
<h2><a name="F1">F1. Why does my old .fetchmailrc file no longer work?</a></h2>
<h3>If your file predates 5.1.0</h3>
In 5.1.0, the <tt>auth</tt> keyword and option were changed to
<tt>preauth</tt>.<p>
<h3>If your file predates 4.5.5</h3>
If the <code>dns</code> option is on (the default), you may need to
make sure that any hostname you specify (for mail hosts or for an SMTP
target) is a canonical fully-qualified hostname). In order to avoid
DNS overhead and complications, fetchmail no longer tries to derive
the fetchmail client machine's canonical DNS name at startup.<P>
<h3>If your file predates 4.0.6:</h3>
Just after the `<CODE>via</CODE>' option was introduced, I realized
that the interactions between the `<CODE>via</CODE>',
`<CODE>aka</CODE>', and `<CODE>localdomains</CODE>' options were out
of control. Their behavior had become complex and confusing, so much so
that I was no longer sure I understood it myself. Users were being
unpleasantly surprised.<P>
Rather than add more options or crock the code, I re-thought it. The
redesign simplified the code and made the options more orthogonal, but
may have broken some complex multidrop configurations.
Any multidrop configurations that depended on the name just after the
`<CODE>poll</CODE>' or `<CODE>skip</CODE>' keyword being still
interpreted as a DNS name for address-matching purposes, even in the
presence of a `<CODE>via</CODE>' option, will break.<P>
It is theoretically possible that other unusual configurations (such
as those using a non-FQDN poll name to generate Kerberos IV tickets) might
also break; the old behavior was sufficiently murky that we can't be
sure. If you think this has happened to you, contact the maintainer.<P>
<h3>If your file predates 3.9.5:</h3>
The `<code>remote</code>' keyword has been changed to `<code>folder</code>'.
If you try to use the old keyword, the parser will utter a warning.<P>
<h3>If your file predates 3.9:</h3>
It could be because you're using a .fetchmailrc that's written in the
old popclient syntax without an explicit `<CODE>username</CODE>'
keyword leading the first user entry attached to a server entry.
This error can be triggered by having a user option such as `<CODE>keep</CODE>'
or `<CODE>fetchall</CODE>' before the first explicit username. For
example, if you write<p>
<pre>
poll openmail protocol pop3
keep user "Hal DeVore" there is hdevore here
</pre>
the `<CODE>keep</CODE>' option will generate an entire user entry with
the default username (the name of fetchmail's invoking user).<p>
The popclient compatibility syntax was removed in 4.0. It complicated
the configuration file grammar and confused users.<p>
<h3>If your file predates 2.8:</h3>
The `<CODE>interface</CODE>', `<CODE>monitor</CODE>' and
`<CODE>batchlimit</CODE>' options changed after 2.8.<p>
They used to be global options with `<CODE>set</CODE>' syntax like the
batchlimit and logfile options. Now they're per-server options, like
`<CODE>protocol</CODE>'.<p>
If you had something like<p>
<pre>
set interface = "sl0/10.0.2.15"
</pre>
in your .fetchmailrc file, simply delete that line and insert
`interface sl0/10.0.2.15' in the server options part of your `defaults'
declaration.<p>
Do similarly for any `<CODE>monitor</CODE>' or `<CODE>batchlimit</CODE>' options.<p>
<hr>
<h2><a name="F2">F2. The .fetchmailrc parser won't accept my all-numeric user name.</a></h2>
Either upgrade to a post-5.0.5 fetchmail or put string quotes around it. :-)<p>
The configuration file parser in older fetchmail versions treated any
all-numeric token as a number, which confused it when it was
expecting a name. String quoting forces the token's class.<p>
The lexical analyzer in 5.0.6 and beyond is smarter and assumes
any token following "username" or "password" is a string.
<hr>
<h2><a name="F3">F3. The .fetchmailrc parser won't accept my host or username beginning with `no'.</a></h2>
See <a href="#F2">F2</a> You're caught in an unfortunate crack between
the newer-style syntax for negated options (`no keep', `no rewrite'
etc.) and the older style run-on syntax (`nokeep', `norewrite'
etc.).<p>
Upgrade to a 5.0.6 or later fetchmail, or put string quotes around your
token.<p>
<hr>
<h2><a name="F4">F4. I'm getting a `parse error' message I don't understand.</a></h2>
The most common cause of mysterious parse errors is putting a server
option after a user option. Check the manual page; you'll probably
find that by moving one or more options closer to the `poll' keyword
you can eliminate the problem.<p>
Yes, I know these ordering restrictions are hard to understand.
Unfortunately, they're necessary in order to allow the `defaults'
feature to work.<P>
<hr>
<h2><a name="F5">F5. The %h and %p escapes aren't being interporated correctly.</a></h2>
Note that %h and %p are only recognized as placeholders if they are a
single word each; you cannot use %h:%p or other interpolations that
aren't space-delimited. If you happen to need such a thing, write a
wrapper. For example, in .fetchmailrc you can add this line:<p>
<pre>
plugin 'mywrap.sh %h %p'
</pre>
With mywrap.sh containing:<p>
<pre>
#! /bin/sh
if test $# -ne 2 ; then
echo "usage: `basename $0` <host> <port>"
exit 1
fi
exec openssl 2>/dev/null s_client -connect $1:$2 -quiet
exit 2 # never reached unless openssl fails
</pre>
<hr>
<h2><a name="C1">C1. Why do I need a .fetchmailrc when running as root on my own machine?</a></h2>
Ian T. Zimmerman <itz@rahul.net> asked:<p>
On the machine where I'm the only real user, I run fetchmail as root
from a cron job, like this:<p>
<pre>
fetchmail -u "itz" -p POP3 -s bolero.rahul.net
</pre>
This used to work as is (with no .fetchmailrc file in root's home
directory) with the last version I had (1.7 or 1.8, I don't
remember). But with 2.0, it RECPs all mail to the local root user,
unless I create a .fetchmailrc in root's home directory containing:<p>
<pre>
skip bolero.rahul.net proto POP3
user itz is itz
</pre>
It won't work if the second line is just "<CODE>user itz</CODE>". This is silly.<p>
It seems fetchmail decides to RECP the `default local user' (i.e. the
uid running fetchmail) unless there are local aliases, and the
`default' aliases (itz->itz) don't count. They should.<p>
Answer:<p>
No they shouldn't. I thought about this for a while, and I don't much
like the conclusion I reached, but it's unavoidable. The problem is
that fetchmail has no way to know, in general, that a local user `itz'
actually exists.<p>
"Ah!" you say, "Why doesn't it check the password file to see if the remote
name matches a local one?" Well, there are two reasons.<p>
One: it's not always possible. Suppose you have an SMTP host declared
that's not the machine fetchmail is running on? You lose.<p>
Two: How do you know server itz and SMTP-host itz are the same person?
They might not be, and fetchmail shouldn't assume they are unless
local-itz can explicitly produce credentials to prove it (that is, the
server-itz password in local-itz's .fetchmailrc file.).<p>
Once you start running down possible failure modes and thinking about
ways to tinker with the mapping rules, you'll quickly find that all the
alternatives to the present default are worse or unacceptably
more complicated or both.<p>
<hr>
<h2><a name="C2">C2. How can I arrange for a fetchmail daemon to get killed when I log out?</a></h2>
The easiest way to dispatch fetchmail on logout (which will work
reliably only if you have just one login going at any time) is to
arrange for the command `fetchmail -q' to be called on logout. Under
bash, you can arrange this by putting `fetchmail -q' in the file
`~/.bash_logout'. Most csh variants execute `~/.logout' on logout.
For other shells, consult your shell manual page.<p>
Automatic startup/shutdown of fetchmail is a little harder to arrange
if you may have multiple login sessions going. In the contrib
subdirectory of the fetchmail distribution there is some shell code
you can add to your .bash_login and .bash_logout profiles that will
accomplish this. Thank James Laferriere <babydr@nwrain.net> for
it.<p>
Some people start up and shut down fetchmail using the ppp-up and
ppp-down scripts of pppd.<p>
<hr>
<h2><a name="C3">C3. How do I know what interface and address to use with --interface?</a></h2>
This depends a lot on your local networking configuration (and right
now you can't use it at all except under Linux and the newer BSDs). However,
here are some important rules of thumb that can help. If they don't
work, ask your local sysop or your Internet provider.<p>
First, you may not need to use --interface at all. If your machine
only ever does SLIP or PPP to one provider, it's almost certainly by a
point to point modem connection to your provider's local subnet that's
pretty secure against snooping (unless someone can tap your phone or
the provider's local subnet!). Under these circumstances, specifying
an interface address is fairly pointless.<p>
What the option is really for is sites that use more than one
provider. Under these circumstances, typically one of your provider
IP addresses is your mailserver (reachable fairly securely via the
modem and provider's subnet) but the others might ship your packets
(including your password) over unknown portions of the general
Internet that could be vulnerable to snooping. What you'll use
--interface for is to make sure your password only goes over the
one secure link.<p>
To determine the device:<p>
<ol>
<li> If you're using a SLIP link, the correct device is probably sl0.
<li> If you're using a PPP link, the correct device is probably ppp0.
<li> If you're using a direct connection over a local network such as
an ethernet, use the command `netstat -r' to look at your routing table.
Try to match your mailserver name to a destination entry; if you don't
see it in the first column, use the `default' entry. The device name
will be in the rightmost column.
</ol>
To determine the address and netmask:<p>
<ol>
<li> If you're talking to slirp, the correct address is probably 10.0.2.15,
with no netmask specified. (It's possible to configure slirp to present
other addresses, but that's the default.)
<li> If you have a static IP address, run `ifconfig <device>', where <device>
is whichever one you've determined. Use the IP address given after
"inet addr:". That is the IP address for your end of the link, and is
what you need. You won't need to specify a netmask.
<li> If you have a dynamic IP address, your connection IP will vary randomly
over some given range (that is, some number of the least significant bits
change from connection to connection). You need to declare an address
with the variable bits zero and a complementary netmask that sets
the range.
</ol>
To illustrate the rule for dynamic IP addresses, let's suppose you're
hooked up via SLIP and your IP provider tells you that the dynamic
address pool is 255 addresses ranging from 205.164.136.1 to
205.164.136.255. Then<p>
<pre>
interface "sl0/205.164.136.0/255.255.255.0"
</pre>
would work. To range over any value of the last two octets
(65536 addresses) you would use<p>
<pre>
interface "sl0/205.164.0.0/255.255.0.0"
</pre>
<hr>
<h2><a name="C4">C4. How can I set up support for sendmail's anti-spam features?</a></h2>
This answer covers versions of sendmail from 8.8.7 (the version
installed in Red Hat 5.1) upwards. If you have an older version,
upgrade to sendmail 8.9.<P>
Stock sendmails can now do anti-spam exclusions based on a database of
filter rules. The human-readable form of the database is at
<tt>/etc/mail/deny</tt>. The database itself is at
<tt>/etc/mail/deny.db</tt>.<P>
The table itself uses email addresses, domain names, and network
numbers as keys. For example,</P>
<PRE>
spammer@aol.com REJECT
cyberspammer.com REJECT
192.168.212 REJECT
</PRE>
<P>would refuse mail from spammer@aol.com, any user from
cyberspammer.com (or any host within the cyberspammer.com domain), and
any host on the 192.168.212.* network. (This feature can be used to
do other things as well; see the <a
href="http://www.sendmail.org/m4/anti-spam.html">sendmail
documentation</a> for details)</P>
To actually set up the database, run
<pre>
makemap hash deny <deny
</pre>
in /etc/mail.<P>
To test, send a message to your mailing address from that host and
then pop off the message with fetchmail, using the -v argument. You
can monitor the SMTP transaction, and when the FROM address is parsed,
if sendmail sees that it is an address in spamlist, fetchmail will
flush and delete it.<p>
Under no circumstances put your <strong>mailhost</strong> or <strong>any host
you accept mail from</strong> using fetchmail into your reject file. You
<strong>will</strong> lose mail if you do this!!!<p>
<hr>
<h2><a name="C5">C5. How can I poll some of my mailboxes more/less
often than others?</a></h2>
Use the <cite>interval</cite> keyword on the ones that should be
checked less often. For example, if you do a poll every 5 minutes,
and want to poll some mailboxes every 5 minutes and some every 30
minutes, use something like this:<p>
<pre>
poll mainsite.example.com proto pop3 user ....
poll secondary.example.com proto pop3 interval 6 user ...
</pre>
Then secondary.example.com will be polled every 6th time that
mainsite.example.com is polled, which with a polling interval of every
5 minutes means that secondary.example.com will be polled every 30
minutes.<p>
<hr>
<h2><a name="C6">Fetchmail works OK started up manually, but not from an init script.</a></h2>
Often, startup scripts have a different environment than an interactive
login shell. For instance, $HOME might point to "/root" when you are
logged in as root, but it might be either unset, or set to "/" when the
startup scripts are running. That means fetchmail at startup can't find
the .fetchmailrc.<p>
Pick a location (such as /etc/fetchmailrc) and use fetchmail's -f
option to point fetchmail at it. That should solve the problem.<p>
<hr>
<h2><a name="C7">C7. How can I forward mail to another host?</a></h2>
To forward mail to a host other than the one you are running fetchmail
on, use the <code>smtphost</code> or <code>smtpname</code> option.
See the manual page for details.<p>
<hr>
<h2><a name="T1">T1. How can I use fetchmail with sendmail?</a></h2>
For most sendmails, no special configuration is required. Eric Allman
tells me that if <code>FEATURE(always_add_domain)</code> is included
in sendmail's configuration, you can leave the <code>rewrite</code>
option off.<P>
If your sendmail complains ``sendmail does not relay'', make sure
your sendmail.cf file says <code>Cwlocalhost</code>
so that sendmail recognizes `localhost' as a name of its host.<p>
If you're mailing from another machine on your local network, also
ensure that its IP address is listed in ip_allow or name in name_allow
(usually in /etc/mail/)<p>
If you find that your sendmail doesn't like the address
`FETCHMAIL-DAEMON@localhost' (which is used in the bouncemail
that fetchmail generates), you may have to set
<code>FEATURE(accept_unqualified_senders)</code>.<P>
Günther Leber reports that Digital Unix sendmails won't work with
fetchmail. The symptom is an error message "<code>553 Local configuration
error, hostname not recognized as local</code>". The problem is that
fetchmail normally feeds sendmail with the client machine's host
address in the MAIL FROM line. These sendmails think this means
they're seeing the result of a mail loop and suppress the mail. You
may be able to work around this by running in <code>--invisible</code> mode.<P>
If you want to support multidrop mode, and you can get access to your
mailserver's sendmail.cf file, it's a good idea to add this rule:<P>
<pre>
H?l?Delivered-To: $h
</pre>
This will cause the mailserver's sendmail to reliably write the
appropriate envelope address into each message before fetchmail sees
it, and tell fetchmail which header it is. With this change,
multidrop mode should work reliably even when the Received header
omits the envelope address (which will typically be the case when
the message has multiple recipients). However it will still not
distinguish the recipients, your only advantage is that no bounce
will be sent if a message is BCC addressed to multiple users at
your site. To fix even that problem, you might want to try the
following hack, which is however untested and quite experimental:<P>
<PRE>
H?J?Delivered-To: $u
Mmdrop, P=/usr/bin/procmail, F=lsDFMqSPfhnu9J,
S=EnvFromSMTP/HdrFromSMTP, R=EnvToSMTP/HdrToSMTP,
T=DNS/RFC822/X-Unix,
A=procmail -Y -a $u -d $h
</PRE>
For both hacks, you have to declare `<CODE>envelope "Delivered-To:"</CODE>' on
the fetchmail side, to put the virtual domain (e.g. `domain.com')
with RELAY permission into your access file and to add a line
reading `<CODE>domain.com local:local-pop-user</CODE>' for the first and
`<CODE>domain.com mdrop:local-pop-user</CODE>' for the second hack to your
mailertable.<P>
You will notice that if the mail already has a Delivered-To header,
sendmail will not add another. Further, editing sendmail.cf
directly is not very comfortable. Solutions for both problems
can be found in Peter `Rattacresh' Backes' `hybrid' patch against
sendmail. Have a look at it, you can find it in the contrib
subdirectory.<P>
Feel free to try Martijn Lievaart's detailed recipe in the contrib
subdirectory of the fetchmail source distribution, it attempts
to realize multidrop mailboxes with an external script.<P>
<hr>
<h2><a name="T2">T2. How can I use fetchmail with qmail?</a></h2>
Turn on the <CODE>forcecr</CODE> option; qmail's listener mode doesn't like
header or message lines terminated with bare linefeeds.<p>
(This information is thanks to Robert de Bath
<robert@mayday.cix.co.uk>.)<p>
If a mailhost is using the qmail package (see <a
href="http://pobox.com/~djb/qmail.html">http://pobox.com/~djb/qmail.html</a>)
then, providing the local hosts are also using qmail, it is possible
to set up one fetchmail link to be reliably collect the mail for an
entire domain.<p>
One of the basic features of qmail is the `Delivered-To:' message
header. Whenever qmail delivers a message to a local mailbox it puts
the username and hostname of the envelope recipient on this line. The
major reason for this is to prevent mail loops. <p>
To set up qmail to batch mail for a disconnected site the ISP-mailhost
will have normally put that site in its `virtualhosts' control file so
it will add a prefix to all mail addresses for this site. This results
in mail sent to 'username@userhost.userdom.dom.com' having a
'Delivered-To:' line of the form:<p>
<pre>
Delivered-To: mbox-userstr-username@userhost.userdom.dom.com
</pre>
A single host maildrop will be slightly simpler:
<pre>
Delivered-To: mbox-userstr-username@userhost.dom.com
</pre>
The ISP can make the 'mbox-userstr-' prefix anything they choose
but a string matching the user host name is likely.<p>
To use this line you must:<p>
<ol>
<li>Ensure the option `envelope Delivered-To:' is in the fetchmail
config file.
<li>Ensure you have a localdomains containing 'userdom.dom.com' or
`userhost.dom.com' respectively.
</ol>
So far this reliably delivers messages to the correct machine of the
local network, to deliver to the correct user the 'mbox-userstr-'
prefix must be stripped off of the user name. This can be done by
setting up an alias within the qmail MTA on each local machine.
Simply create a dot-qmail file called '.qmail-mbox-userstr-default'
in the alias directory (normally /var/qmail/alias) with the contents:<p>
<pre>
| ../bin/qmail-inject -a -f"$SENDER" "${LOCAL#mbox-userstr-}@$HOST"
</pre>
Note this <em>does</em> require a modern /bin/sh.<p>
Peter Wilson adds: <P>
``My ISP uses "alias-unzzippedcom-" as the prefix, which means that I
need to name my file ".qmail-unzzippedcom-default". This is due to
qmail's assumption that a message sent to user-xyz is handled by the
file ~user/.qmail-xyz (or ~user/.qmail-default).''<p>
Luca Olivetti adds:<P>
If you aren't using qmail locally, or you don't want to set up the
alias mechanism described above, you can use the option `<code>qvirtual
"mbox-userstr-"</code>' in your fetchmail config file to strip the prefix
from the local user name.<p>
<hr>
<h2><a name="T3">T3. How can I use fetchmail with exim?</a></h2><p>
If you have <CODE>rewrite</CODE> on: <P>
There is an RFC1123 requirement that MAIL FROM and RCPT TO addresses
you pass to it have to be canonical (e.g. with a fully qualified
hostname part). Therefore fetchmail tries to pass fully qualified
RCPT TO addresses. But exim does not by default accept `localhost' as
a fully qualified domain. This can be fixed.<P>
In exim.conf, add `localhost' to your local_domains declaration if it's not
already present. For example, the author's site at thyrsus.com would
have a line reading:<P>
<pre>
local_domains = thyrsus.com:localhost
</pre>
If you have <CODE>rewrite</CODE> off:<P>
MAIL FROM is a potential problem if the MTAs upstream from your fetchmail
don't necessarily pass canonicalized From and Return-Path addresses,
and fetchmail's <CODE>rewrite</CODE> option is off. The specific case
where this has come up involves bounce messages generated by sendmail
on your mailer host, which have the (un-canonicalized) origin address
MAILER-DAEMON.<p>
The right way to fix this is to enable the <CODE>rewrite</CODE> option and
have fetchmail canonicalize From and Return-Path addresses with the
mailserver hostname before exim sees them. This option is enabled by
default, so it won't be off unless you turned it off.<p>
If you must run with <CODE>rewrite</CODE> off, there is a switch in exim's
configuration files that allows it to accept domainless MAIL FROM
addresses; you will have to flip it by putting the line <p>
<pre>
sender_unqualified_hosts = localhost
</pre>
in the main section of the exim configuration file. Note that this
will result in such messages having an incorrect domain name attached
to their return address (your SMTP listener's hostname rather than
that of the remote mail server). <p>
<hr>
<h2><a name="T4">T4. How can I use fetchmail with smail?</a></h2><p>
Smail 3.2 is very nearly plug-compatible with sendmail, and may work
fine out of the box.<P>
We have one report that when processing multiple messages from a
single fetchmail session, smail sometimes delivers them in an
order other than received-date order. This can be annoying because it
scrambles conversational threads. This is not fetchmail's problem,
it is an smail `feature' and has been reported to the maintainers
as a bug.<P>
Very recent smail versions require an <code>-smtp_hello_verify</code>
option in the smail config file. This overrides smail's check to see
that the HELO address is actually that of the client machine, which
is never going to be the case when fetchmail is in the picture.
According to RFC1123 an SMTP listener <em>must</em> allow this
mismatch, so smail's new behavior (introduced sometime between
3.2.0.90 and 3.2.0.95) is a bug.<P>
<hr>
<h2><a name="T5">T5. How can I use fetchmail with SCO's MMDF?</a></h2><p>
MMDF itself is difficult to configure, but it turns out that
connecting fetchmail to MMDF's SMTP channel isn't that hard.
You can read an <a
href="http://www.aplawrence.com/Unixart/uucptofetch.html">
MMDF recipe</a> that describes replacing a UUCP link with
fetchmail feeding MMDF.<P>
<hr>
<h2><a name="T6">T6. How can I use fetchmail with Lotus Notes?</a></h2><p>
The Lotus Notes SMTP gateway tries to deduce when it should convert \n
to \r\n, but its rules are not the intuitive and correct-for-RFC822
ones. Use `forcecr'.<P>
<hr>
<h2><a name="S1">S1. How can I use fetchmail with qpopper?</a></h2>
Qualcomm's qpopper is probably the best-of-breed among POP3 servers, and
is very widely deployed. Nevertheless, it has some problems which
fetchmail exposes. We recommend using <a href="#G7">IMAP</a> instead if at
all possible. If you must talk to qpopper, here are some problems to
be aware of:<p>
<h3>Problems with retrieving large messages from qpopper 2.53</h3>
Tony Tang <a href="mailto:tony@atn.com.hk"><tony@atn.com.hk></a>
reports that there is a bad intercation between fetchmail and qpopper
2.5.3 under Red Hat Linux versions 5.0 to 5.2, kernels 2.0.34 to
2.0.35. When fetching very large messages (over 700K) from 2.5.3,
fetchmail will hang with a socket error.<p>
This is probably not a fetchmail bug, but rather a symptom of some
problem in the networking stack that qpopper's transmission pattern is
tickling, as fetchpop (another Linux POP client) also displays the hang
but Netscape running under Win95 does not. The problem can also be
banished by <a
href="http://www.eudora.com/freeware/qpop.html">upgrading to qpopper
3.0b1</a>.<p>
<h3>Bad interaction with fetchmail 4.4.2 to 4.4.7</h3>
Versions of fetchmail from 4.4.2 through 4.4.7 had a bad interaction
with Eudora qpopper versions 2.3 and later. See <a href="#X5">X5</a>
for details. The solution is to upgrade your fetchmail.<p>
<hr>
<h2><a name="S2">S2. How can I use fetchmail with Microsoft Exchange?</a></h2>
Fetchmail now supports the proprietary NTLM mode used with M$ Exchange
servers. To enable this, configure fetchmail with the --enable-NTLM
option and recompile it. Note: if you specify a user option value
that looks like `user@domain', the part to the left of the @ will
be passed as the username and the part to the right as the NTLM domain.<P>
M$ Exchange violates the POP3 RFCs. Its LIST command does not reveal
the real sizes of mail in the pop mailbox, but the sizes of the
compressed versions in the exchange mail database (thanks to Arjan De
Vet and Guido Van Rooij for alerting us to this problem).<P>
Fetchmail works with M$ Exchange, despite this brain damage. Two
features are compromised. One is that the --limit option will not
work right (it will check against compressed and not actual sizes).
The other is that a too-small SIZE argument may be passed to your
ESMTP listener, assuming you're using one (this should not be a
problem unless the actual size of the message is above the listener's
configured length limit).<P>
Somewhat belatedly, I've learned that there's supposed to be a
registry bit that can fix this breakage:<P>
<pre>
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MsExchangeIs\Parameters
System\Pop3 Compatibility
</pre>
This is a bitmask that controls the variations from the standard protocol.
The bits defined are:<P>
<DL>
<DT>0x00000001:
<DD>Report exact message sizes for the LIST command
<DT>0x00000002:
<DD>Allow arbitrary linear whitespace between commands and arguments
<DT>0x00000004:
<DD>Enable the LAST command
<DT>0x00000008:
<DD>Allow an empty PASS command (needed for users with blank
passwords, but illegal in the protocol)
<DT>0x00000010:
<DD>Relax the length restrictions for arguments to commands (protocol
requires 40, but some user names may be longer than that).
<DT>0x00000020:
<DD>Allow spaces in the argument to the USER command.
</DL>
There's another one that may be useful to know about:<P>
<pre>
KEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MsExchangeIs\Parameters
System\Pop3 Performance
</pre>
<DL>
<DT>0x00000001:
<DD>Render messages to a temporary stream instead of sending directly
from the database (should always be on)
<DT>0x00000002:
Flag unrenderable messages (instead of just failing commands)
(should only be on if you are seeing the problems reported
in KB Q168109)
<DT>0x00000004:
<DD>Return from the QUIT command before all messages have been deleted.
</DL>
The Microsoft pod-person who revealed this information to me admitted
that he couldn't find it anywhere in their public knowledge base.<P>
Another specific problem we have seen with Exchange servers has as its
symptom a response to LOGIN that says "NO Ambiguous Alias". Grant
Edwards writes:
This means that Exchange Server is too f*&#ing stupid to figure
out which mailbox belongs to you. Instead of actually keeping
track of which inbox belongs to which user, it uses some
half-witted, guess-o-matic heuristic to try to guess your
mailbox name from your username.<p>
In your case it doesn't work because your username maps to more
than one mailbox. For some people it doesn't work because
their username maps to zero mailboxes. This is yet another
inept, lame, almost criminally negligent design decision from
our friends in Redmond.<p>
You've got several options:
<ul>
<li>
Try giving fetchmail a username of "/NTDomain/NTUsername/MailboxName".
<li>
Get your administrator to configure the server so that
usernames and mailbox names are the same.
<li>
Get your administrator to add an alias that maps your
username explicitly to your mailbox name.
</ul>
But, the best option involves a tactical nuclear weapon (an old
ASROC will do), pissing off a lot people who live downwind from
Redmond, and your choice of any Linux, NetBSD, FreeBSD, or
Solaris CD.<p>
I'll provide the CD.
<hr>
<h2><a name="S3">S3. How can I use fetchmail with CompuServe RPA?</a></h2>
First, make sure your fetchmail has the RPA support compiled in.
Stock fetchmail binaries (such as you might get from an RPM) don't.
You can check this by looking at the output of <code>fetchmail -V</code>;
if you see the string "+RPA" after the version ID you're good to go,
otherwise you'll have to build your own from sources (see the INSTALL
file in the source distribution for directions).<P>
Give your CompuServe pass-phrase in lower case as your password. Add
`@compuserve.com' to your user ID so that it looks like `user
<UserID>@compuserve.com', where <UserID> can be either
your numerical userID or your E-mail nickname. An RPA-enabled
fetchmail will automatically check for csi.com in the POP server's
greeting line. If that's found, and your user ID ends with
`@compuserve.com', it will query the server to see if it
is RPA-capable, and if so do an RPA transaction rather than a
plain-text password handshake.<P>
<strong>Warning:</strong> the debug (-v -v) output of fetchmail will show
your pass-phrase in Unicode!<P>
These two .fetchmailrc entries show the difference between an RPA and
non-RPA configuration:
<pre>
# This version will use RPA
poll csi.com via "pop.site1.csi.com" with proto POP3 and options no dns
user "CSERVE_USER@compuserve.com" there with password "CSERVE_PASSWORD"
is LOCAL_USER here options fetchall stripcr
# This version will not use RPA
poll non-rpa.csi.com via "pop.site1.csi.com" with proto POP3 and options no dns
user "CSERVE_USER" there with password "CSERVE_POP3_PASSWORD"
is LOCAL_USER here options fetchall stripcr
</pre>
<hr>
<h2><a name="S4">S4. How can I use fetchmail with Demon Internet's SDPS?</a></h2>
<h3>Single-drop mode</h3>
You can get fetchmail to download the email for just one user from
Demon Internet's POP3 server by giving it a username consisting of your
Demon user name followed by your account name, with an at-sign between
them.<P>
For example, to download email for the user <philh@vision25.demon.co.uk>,
you could use the following .fetchmailrc file:<P>
<pre>
set postmaster "philh"
poll pop3.demon.co.uk with protocol POP3:
user "philh@vision25" is philh
</pre>
<h3>Multi-drop mode</h3>
Demon Internet's SDPS service is an implementation of POP3. All messages
have a Received: header added when they enter the maildrop, like this:
<pre>
Received: from punt-1.mail.demon.net by mailstore.com for fred@xyz.demon.co.uk
id 899963657:10:27896:0; Thu, 09 Jul 98 05:54:17 GMT
</pre>
To enable multi-drop mode you need to tell fetchmail that 'mailstore.com' is
the name of the host which accepted the mail, and let it know the
hostname part(s) of your E-mail address. The following example assumes
that your hostname is xyz.demon.co.uk, and that you have also bought
"mail forwarding" for the domain my-company.co.uk (in which case your
MTA must also be configured to accept mail sent to user@my-company.co.uk)
<pre>
poll pop3.demon.co.uk proto pop3 aka mailstore.com no dns:
localdomains xyz.demon.co.uk my-company.co.uk
user xyz is * fetchall
</pre>
The `fetchall' command ensures that all mail is downloaded. If you
want to leave mail on the server use `uidl' and `keep'; Demon does not
implement the obsolete `top' command, because SDPS combines messages
residing on two separate punt clusters into a single POP3 maildrop.
If you do use UIDL, be aware that the "user@host" form for fetching
mail from a particular Demon host will confuse fetchmail's UIDL code;
use user+host.<P>
Note that Demon may delete mail on the server which is more than 30
days old; see their <a
href="http://www.demon.net/info/helpdesk/demon_products/mail/sdps-tech.shtml">
POP3 page</a> for details.<P>
<h3>The SDPS extension</h3>
There's a different way to do multidrop. It's not necessary on Demon
Internet, since fetchmail can parse Received addresses, but the person
who implemented this didn't know that. It may be useful if Demon
Internet ever changes mail transports.<P>
SDPS includes a non-standard extension for retrieving the envelope of a
message (*ENV), which fetchmail optionally supports if compiled with the
--enable-SDPS option. If you have it, the first line of the fetchmail -V
response will include the string "+SDPS".<P>
Once you have SDPS compiled in, fetchmail in POP3 mode will
automatically detect when it's talking to a Demon Internet host in
multidrop mode, and use the *ENV extension to get an envelope To address.<P>
The autodetection works by looking at the hostname in the POP3
greeting line; if you're accessing Demon Internet through a proxy it
may fail. To force SDPS mode, pick "sdps" as your protocol.<P>
<hr>
<h2><a name="S5">S5. How can I use fetchmail with usa.net's servers?</a></h2>
Enable `<CODE>fetchall</CODE>'. A user reports that the 2.2 version
of USA.NET's POP server reports that you must use the
`<CODE>fetchall</CODE>' option to make sure that all of the mail is
retrieved, otherwise some may be left on the server. This is almost
certainly a server bug.<P>
The usa.net servers (at least in their 2.2 version, June 1998) don't
handle the TOP command properly, either. Regardless of the argument
you give it, they retrieve only about 10 lines of the message.
Fetchmail normally uses TOP for message retrieval in order to avoid
marking messages seen, but `<CODE>fetchall</CODE>' forces it to use
RETR instead.<P>
(Note: Other failure modes have been reported on usa.net's servers.
They seem to be chronically flaky. We recommend finding another
provider.)<P>
<hr>
<h2><a name="S6">S6. How can I use fetchmail with HP OpenMail?</a></h2>
No special configuration is required, but OpenMail versions prior to
6.0 have an annoying bug similar to the big one in <a
href="#S2">Microsoft Exchange</a>. The message sizes it gives in the
LIST are rounded to the nearest 1024 bytes. It also has a nasty habit
of discarding headers it doesn't recognize, such as X- and Resent-
headers.<P>
As with M$ Exchange, the only real fix for these problems is to get a
POP (or preferably IMAP) server that isn't brain-dead. OpenMail's
project manager claims these bugs have been fixed in 6.0.<P>
<hr>
<h2><a name="S8">S8. How can I use fetchmail with Hotmail?</a></h2>
You can't, yet. But <a
href="http://www.ozemail.com.au/~peterhawkins/gotmail/">gotmail</a>
might be what you need.<P>
<hr>
<h2><a name="S9">S9. How can I use fetchmail with MSN?</a></h2>
You can't. MSN uses something that looks like POP3, except the
authentication part is nonstandard. And of course they don't
document it, so nobody but their Windows clients can speak it.<p>
This is a customer lock-in tactic; we recommend boycotting MSN as the
only appropriate response.<p>
As of 5.0.8, we have support for the client side of NTLM
authentication. It's possible this may enable fetchmail to talk to
MSN; if so, somebody should report it so this FAQ can be corrected.<p>
<hr>
<h2><a name="S10">S10. How can I use fetchmail with SpryNet?</a></h2>
The SpryNet POP3 servers mark a message queried with TOP as seen.
This means that if your connection drops in mid-message, it may end
up invisibly stuck on your mail spool. Use the <code>fetchall</code>
flag to ensure that it's recovered on the next cycle.<p>
<hr>
<h2><a name="S11">S11. How can I use fetchmail with FTGate?</a></h2>
The FTGate V2 server (and possibly older versions as well) has a weird
bug. It answers OK twice to a TOP request! Use the
<code>fetchall</code> option to force use of RETR and work around this
bug.<p>
<hr>
<h2><a name="S12">S12. How can I use fetchmail with MailMax?</a></h2>
You can't. At least not if you want to be able to see attachments.
MailMax has a bug; it reports the message length with attachments
but doesn't download them on TOP or RETR.<P>
Also, we're told that TOP sometimes fails to retrieve the entire
message even when enough lines have been specified. The MailMax
developers have acknowledged this bug as of 4 May 2000, but there is
no fix yet. If you must use this server, force RETR with the
<tt>fetchall</tt> option.<p>
<hr>
<h2><a name="S13">S13. How can I use fetchmail with Novell GroupWise?</a></h2>
The Novell GroupWise IMAP server would be better named GroupFoolish;
it is (according to the designer of IMAP) unusably broken. Among
other things, it doesn't include a required content length in its
BODY[TEXT] response.<p>
Fetchmail works around this problem, but we strongly recommend voting
with your dollars for a server that isn't brain-dead. If you stick
with code as shoddy as GroupWise seems to be, you will probably pay
for it with other problems.<p>
<hr>
<h2><a name="S14">S14. How can I use fetchmail with InterChange?</a></h2>
You can't. At least not if you want to be able to see attachments.
InterChange has a bug similar to the MailMax server; it reports the
message length with attachments but doesn't download them on TOP or
RETR. <p>
<hr>
<h2><a name="K1">K1. How can I use fetchmail with SOCKS?</a></h2>
Giuseppe Guerini added a --with-socks option that supports linking
with socks library. If you specify the value of this option as
``yes'', the configure script will try to find the Rconnect library
and set the makefile up to link it. You can also specify a directory
containing the Rconnect library.<p>
Alan Schmitt has added a similar --with-socks5 option that may work
better if you have a recent version of the SOCKS library.
<hr>
<h2><a name="S7">S7. How can I use fetchmail with geocities POP3 servers?</a></h2>
Nathan Cutler reports that the the mail.geocities.com POP3 servers
fail to include the first Received line of the message in the send to
fetchmail. This can solve problems if your MUA interprets Received
continuations as body lines and doesn't parse any of the following
headers.<P>
Workaround is to use "mda" keyword or "-mda" switch:
<pre>
mda "sed -e '1s/^\t/Received: /' | formail | /usr/bin/procmail -d <user>"
</pre>
Replace \t with exactly one tabulation character.
You should also consider using "fetchall" option because Geocities' servers
sometimes think that the first 45 messages have already been read.<P>
Fix: Get an email provider that doesn't suck. The pop-up ads on
Geocities are lame, you should boycott them anyway.<P>
<hr>
<h2><a name="K2">K2. How can I use fetchmail with IPv6 and IPsec?</a></h2>
To use fetchmail with IPv6, you need a system that supports IPv6, the "Basic
Socket Interface Extensions for IPv6" (RFC 2133).
This currently means that you need to have a BSD/OS or NetBSD system with
the NRL IPv6+IPsec software distribution or a Linux system with a 2.2 or
later kernel and net-tools. It should not be hard to build fetchmail on
other IPv6 implementations if you can port the inet6-apps kit.<P>
To use fetchmail with networking security (read: IPsec), you need a system that
supports IPsec, the API described in the "Network Security API for Sockets"
(draft-metz-net-security-api-01.txt), and the inet6-apps kit. This currently
means that you need to have a BSD/OS or NetBSD system with the NRL IPv6+IPsec
software distribution. A Linux IPsec implementation supporting this API will
probably appear in the coming months.<P>
The NRL IPv6+IPsec software distribution can be obtained from: <a
href="http://web.mit.edu/network/isakmp">http://web.mit.edu/network/isakmp</a>
<P>
The inet6-apps kit can be obtained from <a href="http://ftp.ps.pl/pub/linux/IPv6/inet6-apps/">http://ftp.ps.pl/pub/linux/IPv6/inet6-apps/</a>.<P>
More information on using IPv6 with Linux can be obtained from:
<UL>
<LI>
<a href="http://www.bieringer.de/linux/IPv6/IPv6-HOWTO/IPv6-HOWTO.html">
http://www.bieringer.de/linux/IPv6/IPv6-HOWTO/IPv6-HOWTO.html</a>
<LI>
<a href="http://www.ipv6.inner.net/ipv6">http://www.ipv6.inner.net/ipv6</a>
(via IPv6)
<LI>
<a href="http://www.inner.net/ipv6">http://www.inner.net/ipv6</a> (via IPv4)
</UL>
<hr>
<h2><a name="K3">K3. How can I get fetchmail to work with ssh?</a></h2>
We have five recipes for this.<P>
<h3>Single-User POP3</h3>
First, a lightly edited version of a recipe from Masafumi NAKANE.
This one is easy to set up, but only supports one user at a time.<p>
1. You must have ssh (the ssh client) on the local host and sshd (ssh
server) on the remote mail server. And you have to configure ssh so
you can login to the sshd server host without a password. (Refer to ssh
man page for several authentication methods.)<p>
2. Add something like following to your .fetchmailrc file: <p>
<pre>
poll mailhost port 1234 via localhost with proto pop3:
preconnect "ssh -l username -f mailhost -L 1234:mailhost:110 sleep 5"
</pre>
The sleep is needed on slower machines to prevent fetchmail from
trying to open the socket before ssh actually makes it ready. Faster
machines may not need it.<p>
(Note that 1234 can be an arbitrary port number. Privileged ports can
be specified only by root.) The effect of this ssh command is to
forward connections made to localhost port 1234 (in above example) to
mailhost's 110. <p>
This configuration will enable secure mail transfer. All the
conversation between fetchmail and remote pop server will be
encrypted.<p>
If sshd is not running on the remote mail server, you can specify
intermediate host running it. If you do this, however, communication
between the machine running sshd and the POP server will not be encrypted.
And the preconnect line would be like this:<p>
<pre>
preconnect "ssh -f -L 1234:mailhost:110 sshdhost sleep 20 </dev/null >/dev/null"
</pre>
You can work this trick with IMAP too, but the port number 110 in the
above would need to become 143. In either case you'll have to specify
a password but the password will not be sent in clear.<p>
There is an explanation of a similar recipe at <a
href="http://sunsite.unc.edu/LDP/HOWTO/mini/Secure-POP+SSH.html">Secure
POP via SSH mini-HOWTO</a>.<P>
<h3>Multi-User POP3</h3>
Second, a recipe from Charlie Brady <cbrady@ind.tansu.com.au>:<p>
Charlie says: "The recipe [from Masafume NAKANE] certainly works, but
the solution I post here is better in a few respects":
<UL>
<LI>this method will not fail if two or more users attempt to use fetchmail
simultaneously.
<LI>you are able to use the full facilities of tcpd to control access
<LI>this method does not depend on the preconnect feature of fetchmail, so
can be used for tunneling of other services as well.
</UL>
Here are the steps:
<OL>
<LI>
Make sure that the "socket" program is installed on the server
machine. Presently it lives at <a
href="ftp://sunsite.unc.edu/pub/linux/system/network/misc/socket-1.1.tar.gz">
ftp://sunsite.unc.edu/pub/linux/system/network/misc/socket-1.1.tar.gz</a>,
but watch out for a change in version number.<P>
<LI>
Set up an unprivileged account on your system with a .ssh directory
containing an SSH identity file "identity" with no pass phrase,
"identity.pub" and "known_hosts" containing the host key of your
mailhost. Let's call this account "noddy".
<LI>
On mailhost, set up no-password access for noddy@yourhost. Add to your
SSH authorized_keys file:
<PRE>
command="socket localhost 110",no-port-forwarding 1024 ......
</PRE>
where "<code>1024 ......</code>" is the content of noddy's identity.pub file.
<LI>
Create a script /usr/local/bin/ssh.fm and make it executable:
<PRE>
#! /bin/sh
exec ssh -q -C -l your.login.id -e none mailhost socket localhost 110
</PRE>
<LI>
Add an entry in inetd.conf for whatever port you choose to use - say:
<PRE>
1234 stream tcp nowait noddy /usr/sbin/tcpd /usr/local/bin/ssh.fm
</PRE>
<LI>
Send a HUP signal to your inetd.
</OL>
Now just use localhost:1234 to access your POP server.<P>
<h3>Multi-User IMAP</h3>
This one comes comes to us from Joerg Dorchain.
The basic idea is to set up a bidirectional encrypted socket connection:<p>
<pre>
fetchmail <--> ssh <---> sshd <--> imapd
\---local side--/ \-remote side-/
</pre>
Use ssh-keygen(1) to set up a special ssh identity with no password
and RSA-only authentication, which executes /usr/sbin/imapd when
authenticated. For security reasons all other commands should be
disabled. (There is some security exposure in using an identity
without a passphrase; it means anyone who can get access to your
account could use it to read your mail).<p>
Running ssh-keygen will generate two files. Have it create the
private key to ~/.ssh/identity-imap. Once you have generated the
corresponding public key, prepend this to the line of key data in it:
<pre>
command="/usr/sbin/imapd",no-port-forwarding,no-agent-forwarding
</pre>
This identity data has to be appended to ~/.ssh/authorized_keys on the
remote machine, as usual for RSA authentication. Whenever your ssh
uses this identity, the remote side will run imapd. The imapd will
see that it is not running as root and go into preauthenticated
mode.<p>
On the client side, use the <code>plugin</code> keyword to make
fetchmail talk to the stdin of the remote ssh. Here's an examople:
<pre>
poll mail.dorchain.net
with options proto imap, preauth ssh, plugin fetchmail-imap-wrapper
</pre>
The wrapper script should look like this:<p>
<pre>
#!/bin/sh
exec ssh -i $HOME/.ssh/identity-imap $1 /usr/sbin/imapd
</pre>
<h3>Netcat-based POP or IMAP tunnelling</h3>
Oren Tirosh <oren@mimique.com> sends us a method of using
fetchmail over ssh without port forwarding, using the plugin keyword.<P>
First, set up a poll entry resembling thius one:
<TT>
poll target.host plugin sshtunnel proto pop3 user foo password *
</TT>
The important part is the "plugin sshtunnel". Now set up sshtunnel
as follows:<P>
<TT>
This is the sshtunnel script:
#!/bin/sh
ssh $1 "nc localhost $2"
</TT>
Thia method uses netcat to connect to the pop3 port locally on the
target host and create a two-way channel over the ssh connection.<P>
Oren says: "In my experience it is much more reliable than the methods
described in your FAQ. ssh port forwarding often keeps the local port
bound for along timeout and has timing issues requiring tricks like
sleep, etc. I use this method for fetching all the mail for
mimique.com"<P>
<h3>Using plugin</h3>
Since 5.4.5, there's been a very simple recipe. Use the following option:
<TT>
plugin "ssh %h /usr/sbin/rimapd"
</TT>
You may have to use a different absolute pathname. This option tells
fetchmail that instead of opening a connection on the server's port
143 and doing standard IMAP authentication, fetchmail should ssh to
the server and run rimapd, using the more secure ssh authentication
(as well as getting ssh's encryption).<p>
<hr>
<h2><a name="K4">K4. What do I have to do to use the IMAP-GSS protocol?</a></h2>
Fetchmail can use RFC1731 GSSAPI authorization to safely identify you
to your IMAP server, as long as you can share Kerberos V credentials
with your mail host and you have a GSSAPI-capable IMAP server.
UW-IMAP (available via FTP at <a
href="ftp://ftp.cac.washington.edu/mail/">ftp.cac.washington.edu</a>)
is the only one I'm aware of and the one I recommend anyway for other
reasons. You'll need version 4.1-FINAL or greater though, and it has
to have GSS support compiled in.<p>
Neither UW-IMAP nor fetchmail compile in support for GSS by default,
since it requires libraries from the Kerberos V distribution
(available via FTP at <a
href="ftp://athena-dist.mit.edu/pub/ATHENA/kerberos">athena-dist.mit.edu</a>).
If you have these, compiling in GSS support is simple: add a
<pre>--with-gssapi=[/path/to/krb5/root]</pre> option to configure. For
instance, I have all of my Kerberos V libraries installed under
/usr/krb5 so I run <pre>configure --with-gssapi=/usr/krb5</pre><p>
Setting up Kerberos V authentication is beyond the scope of this FAQ
(you may find Jim Rome's paper <a
href="http://www.ornl.gov/~jar/HowToKerb.html"> How to Kerberize your
site</a> helpful), but you'll at least need to add a credential for
imap/[mailhost] to the keytab of the mail server (IMAP doesn't just
use the host key). Then you'll need to have your credentials ready on
your machine (cf. kinit).<p>
After that things are very simple. Set your protocol to imap-gss in your
.fetchmailrc, and omit the password, since imap-gss doesn't need one. You
can specify a username if you want, but this is only useful if your mailbox
belongs to a username different from your Kerberos principal. <p>
Now you don't have to worry about your password appearing in cleartext in
your .fetchmailrc, or across the network.<p>
<hr>
<h2><a name="K5">K5. How can I use fetchmail with SSL?</a></h2>
You'll need to have the <a href="http://www.openssl.org/">OpenSSL</a>
libraries installed. Configure with --with-ssl. If you have the
OpenSSL libraries installed in the default location (/usr/local/ssl)
this will suffice. If you have them installed in a non-default
location, you'll need to specify it as an argument to --with-ssl after
an equal sign.<p>
Fetchmail binaries built this way support <code>ssl</code>,
<code>sslkey</code>, and <code>sslcert</code> options that control
SSL encryption. You will need to have an SSL-enabled mailserver
to use these options. See the manual page for detals.<p>
If your open OpenSSL session dies with a message that complains "PRNG
not seeded", update or improve your operating system. This means that
the OpenSSL library on your machine has been unable to locate a source
of random bits from which to seed its random-number generator;
normally these come from the <tt>/dev/urandom</tt>, and this message
probably means your OS doesn't have that device.<P>.
An interactive program could seed the random number generator from
keystroke timings or some other form of user input. Because fetchmail
is primarily designed to run forever as a background daemon, that option
option is not available in this case.<P>
<hr>
<h2><a name="R1">R1. Fetchmail isn't working, and -v shows `SMTP connect failed' messages.</a></h2>
Fetchmail itself is probably working, but your SMTP port 25 listener
is down or inaccessible.<p>
The first thing to check is if you can telnet to port 25 on your smtp
host (which is normally `localhost' unless you've specified an smtp
option in your .fetchmailrc or on the command line) and get a greeting
line from the listener. If the SMTP host is inaccessible or the listener
is down, fix that first.<p>
In Red Hat Linux 6.9, SMTP is disabled by default. To fix this,
set "DAEMON=yes" in your /etc/sysconfig/sendmail file, then restart
sendmail by running "/sbin/service sendmail restart".<p>
If the listener seems to be up when you test with telnet, the most
benign and typical problem is that the listener had a momentary seizure
due to resource exhaustion while fetchmail was polling it -- process
table full or some other problem that stopped the listener process
from forking. If your SMTP host is not `localhost' or something else
in /etc/hosts, the fetchmail glitch could also have been caused by
transient nameserver failure. <p>
Try running fetchmail -v again; if it succeeds, you had one of these
kinds of transient glitch. You can ignore these hiccups, because a
future fetchmail run will get the mail through. <p>
If the listener tests up, but you have chronic failures trying to
connect to it anyway, your problem is more serious. One way to work
around chronic SMTP connect problems is to use --mda. But this only
attacks the symptom; you may have a DNS or TCP routing problem. You
should really try to figure out what's going on underneath before it
bites you some other way. <p>
We have one report (from toby@eskimo.com) that you can sometimes solve
such problems by doing an <CODE>smtp</CODE> declaration with an IP
address that your routing table maps to something other than the
loopback device (he used ppp0).<p>
We also have a report that this error can be caused by having an
/etc/hosts file that associates your client host name with more than
one IP address.<P>
It's also possible that your DNS configuration isn't
looking at <code>/etc/hosts</code> at all. If you're using libc5,
look at <code>/etc/resolv.conf</code>; it should say something like
<pre>
order hosts,bind
</pre>
so your <code>/etc/hosts</code> file is checked first. If you're
running GNU libc6, check your <code>/etc/nsswitch.conf</code> file. Make
sure it says something like
<pre>
hosts: files dns
</pre>
again, in order to make sure <code>/etc/hosts</code> is seen first.<P>
If you have a hostname set for your machine, and this hostname does
not appear in /etc/hosts, you will be able to telnet to port 25 and
even send a mail with rcpt to: user@host-not-in-/etc/hosts, but
fetchmail can't seem to get in touch with sendmail, no matter what you
set smtpaddress to.<p>
We had another report from a Linux user of fetchmail 2.1 who solved his SMTP
connection problem by removing the reference to -lresolv from his link
line and relinking. Apparently in some older Linux distributions the
libc bind library version works better.<p>
As of 2.2, the configure script has been hacked so the bind library is
linked only if it is actually needed. So under Linux it won't be, and
this particular cause should go away.<p>
<hr>
<h2><a name="R2">R2. When I try to configure an MDA, fetchmail doesn't work.</a></h2>
(I hear this one from people who have run into the blank-line problem in <a href="#X1">X1</a>.)<p>
Try sending yourself test mail and retrieving it using the
command-line options `<CODE>-k -m cat</CODE>'. This will dump exactly what
fetchmail retrieves to standard output (plus the Received line
fetchmail itself adds to the headers). <p>
If the dump doesn't match what shows up in your mailbox when you
configure an MDA, your MDA is mangling the message. If it doesn't
match what you sent, then fetchmail or something on the server is
broken.<p>
<hr>
<h2><a name="R3">R3. Fetchmail dumps core when given an invalid rc file.</a></h2>
This is usually reported from AIX or Ultrix, but has even been known
to happen on Linuxes without a recent version of <code>flex</code>
installed. The problem appears to be a result of building with an
archaic version of lex.<P>
Workaround: fix the syntax of your .fetchmailrc file.<P>
Fix: build and install the latest version of <a
href="ftp://prep.ai.mit.edu/~ftp/pub/gnu">flex</a> from the Free
Software Foundation. An FSF <a
href="http://www.gnu.ai.mit.edu/order/ftp.html">mirror site</a>
will help you get it faster.<P>
<hr>
<h2><a name="R4">R4. Fetchmail dumps core in -V mode, but operates normally otherwise.</a></h2>
We've had this reported to us under Linux using libc-5.4.17 and gcc-2.7.2.
It does not occur with libc-5.3.12 or earlier versions.<p>
Workaround: link with GNU malloc rather than the stock C library malloc.<p>
We're told there is some problem with the malloc() code in that
version which makes it fragile in the presence of multiple free()
calls on the same pointer (the malloc arena gets corrupted).
Unfortunately it appears from doing gdb traces that whatever free()
calls producing the problem are being made by the C library itself, not the
fetchmail code (they're all from within fclose, and not an fclose called
directly by fetchmail, either).<p>
<hr>
<h2><a name="R5">R5. Running fetchmail in daemon mode doesn't work.</a><br></h2>
We have one report from a SunOS 4.1.4 user that trying to run
fetchmail in detached daemon mode doesn't work, but that using the
same options with -N (nodetach) is OK.<P>
If this happens, you have a specific portability problem with the code
in daemon.c that detaches and backgrounds the daemon fetchmail. Tell
me about it so I can try to fix it. As a workaround, you can start
fetchmail with -N and an ampersand to background it. A Sun user
recommends
this:<P>
<PRE>
(fetchmail --nodetach <other params> &)
</PRE>
The extra pair of parens is significant --- it makes sure that the process
detaches from the initial shell (one more shell is started and dies
immediately, detaching fetchmail and making it child of PID 1). This is
important when you start fetchmail interactively and than quit
interactive shell. The line above makes sure fetchmail lives after
that!<p>
This should not happen under Linux or any truly POSIX-conformant Unix.<P>
<hr>
<h2><a name="R6">R6. Fetchmail hangs when used with pppd.</a></h2>
Your problem may be with pppd's `demand' option. We have a report that
fetchmail doesn't play well with it, but works with pppd if `demand'
is turned off. We have no idea why this is.<p>
<hr>
<h2><a name="R7">R7. Fetchmail randomly dies with socket errors.</a></h2>
Check the MTU value in your PPP interface reported by
<code>/sbin/ifconfig</code>. If it's over 600, change it in your PPP
options file. (<code>/etc/ppp/options</code> on my box). Here are
option values that work:<P>
<pre>
mtu 552
mru 552
</pre>
<hr>
<h2><a name="R8">R8. Fetchmail running as root stopped working after an OS upgrade</a></h2>
In RH 6.0, the HOME value in the boot-time root environment changed
from /root to / as the result of a change in init. Move your
.fetchmailrc or use a -f option to explicitly point at the file.
(Oddly, a similar problem has been reported from Debian systems.)<P>
<hr>
<h2><a name="R9">R9. Fetchmail is timing out after fetching certain
messages but before deleting them</a></h2>
There's a TCP/IP stalling problem under Redhat 6.0 (and possibly other
recent Linuxes) that can cause this symptom. Brian Boutel writes:<p>
<blockquote>
TCP timestamps are turned on on my Linux boxes (I assume it's now the
default). This uses 12 extra bytes per segment.
When the tcp connection starts, the other end agrees a MSS of 1460,
and then fragments 1460 byte chunks into 1448 and 12, because
is is not allowing for the timestamp.<p>
Then, for reasons I can't explain, it waits a long time (typically 2
minutes) after the ack is sent before sending the next (fragmented)
packet. Turning off tcp timestamps avoids the fragmentation and
restores normal behaviour. To do this, [execute]<p>
echo 0 > /proc/sys/net/ipv4/tcp_timestamps<p>
I'm still unclear about the details of why this is happening. At least
[now] I am now getting good performance and no queue blocking.
</blockquote>
<hr>
<h2><a name="R10">R10. Fetchmail is timing out during message fetches</a></h2>
This is probably a general networking issue. Sending a "RETR" command will
cause the server to start sending large amounts of data, which means
large packets. If your networking layer has a packet-fragmentation
problem, that's where you'll see it.<p>
<hr>
<h2><a name="D1">D1. I think I've set up fetchmail correctly, but I'm not getting any mail.</a></h2>
Maybe you have a .forward or alias set up that you've forgotten about. You
should probably remove it.<p>
Or maybe you're trying to run fetchmail in multidrop mode as root
without a .fetchmailrc file. This doesn't do what you think it
should; see question <a href="#C1">C1</a>.<p>
Or you may not be connecting to the SMTP listener. Run fetchmail -v
and see <a href="#R1">R1</a>.<p>
<hr>
<h2><a name="D2">D2. All my mail seems to disappear after a dropped connection.</a></h2>
One POP3 daemon used in the Berkeley Unix world that reports itself as
POP3 version 1.004 actually throws the queue away. 1.005 fixed that.
If you're running this one, upgrade immediately. (It also truncates
long lines at column 1024)<P>
Many POP servers, if an interruption occurs, will restore the whole
mail queue after about 10 minutes. Others will restore it right
away. If you have an interruption and don't see it right away, cross
your fingers and wait ten minutes before retrying.<P>
Some servers (such as Microsoft's NTMail) are mis-designed to restore
the entire queue, including messages you have deleted. If you have
one of these and it flakes out on you a lot, try setting a small
<code>--fetchlimit</code> value. This will result in more IP connects
to the server, but will mean it actually executes changes to the queue
more often.<P>
Qualcomm's qpopper, used at many BSD Unix sites, is better behaved.
If its connection is dropped, it will first execute all DELE commands as
though you had issued a QUIT (this is a technical violation of
the POP3 RFCs, but a good idea in a world of flaky phone lines). Then it
will re-queue any message that was being downloaded at hangup time.
Still, qpopper may require a noticeable amount of time to do deletions
and clean up its queue. (Fetchmail waits a bit before retrying in
order to avoid a `lock busy' error.)<P>
<hr>
<h2><a name="D3">D3. Mail that was being fetched when I interrupted my fetchmail seems to have been vanished.</a></h2>
Fetchmail only sends a delete mail request to the server when either
(a) it gets a positive delivery acknowledgment from the SMTP
listener, or (b) it gets an error 571 (the spam-filter error) from the
listener. No interrupt can cause it to lose mail.<p>
However, IMAP2bis has a design problem in that its normal fetch
command marks a message `seen' as soon as the fetch command to get it
is sent down. If for some reason the message isn't actually delivered
(you take a line hit during the download, or your port 25 listener
can't find enough free disk space, or you interrupt the delivery in
mid-message) that `seen' message can lurk invisibly in your server
mailbox forever.<p>
Workaround: add the `<CODE>fetchall</CODE>' keyword to your fetch options.<p>
Solution: switch to an <a href="http://www.imap.org">IMAP4</a> server.<p>
<hr>
<h2><a name="M1">M1. I've declared local names, but all my multidrop
mail is going to root anyway.</a></h2>
Somehow your fetchmail is never recognizing the hostname part of
recipient names it parses out of To/Cc/envelope-header lines as
matching the name of the mailserver machine. To check this, run
fetchmail in foreground with -v -v on. You will probably see a lot of
messages with the format ``line rejected, %s is not an alias of the
mailserver'' or ``no address matches; forwarding to %s.'' <p>
These errors usually indicate some kind of DNS configuration problem
either on the server or your client machine. <p>
The easiest workaround is to add a `<CODE>via</CODE>' option (if
necessary) and add enough aka declarations to cover all of your
mailserver's aliases, then say `<CODE>no dns</CODE>'. This will take
DNS out of the picture (though it means mail may be uncollected if
it's sent to an alias of the mailserver that you don't have
listed). <p>
It would be better to fix your DNS, however. DNS problems can hurt
you in lots of ways, for example by making your machines
intermittently or permanently unreachable to the rest of the net.<P>
Occasionally these errors indicate the sort of header-parsing problem
described in <a href="#M7">M7</a>.<P>
<hr>
<h2><a name="M2">M2. I can't seem to get fetchmail to route to a local domain properly.</a></h2>
A lot of people want to use fetchmail as a poor man's internetwork
mail gateway, picking up mail accumulated for a whole domain in a single
server mailbox and then routing based on what's in the To/Cc/Bcc lines.<p>
In general, this is not really a good idea. It would be smarter to
just let the mail sit in the mailserver's queue and use fetchmail's
ETRN mode to trigger SMTP sends periodically (of course, this means
you have to poll more frequently than the mailserver's expiration period).
If you can't arrange this, try setting up a UUCP feed.<P>
If neither of these alternatives is available, multidrop mode may do
(though you <em>are</em> going to get hurt by some mailing list
software; see the caveats under THE USE AND ABUSE OF MULTIDROP
MAILBOXES on the man page). If you want to try it, the way to do it
is with the `<CODE>localdomains</CODE>' option.<p>
In general, if you use localdomains you need to make sure of two other
things: <p>
<strong>1. You've actually set up your .fetchmailrc entry to invoke multidrop mode.</strong><p>
Many people set a `<CODE>localdomains</CODE>' list and then forget
that fetchmail wants to see more than one name (or the wildcard `*')
in a `<CODE>here</CODE>' list before it will do multidrop routing.<p>
<strong>2. You may have to set `no envelope'.</strong><p>
Normally, multidrop mode tries to deduce an envelope address from a message
before parsing the To/Cc/Bcc lines (this enables it to avoid losing to mailing
list software that doesn't put a recipient address in the To lines).<p>
Some ways of accumulating a whole domain's messages in a single server
mailbox mean it all ends up with a single envelope address that is
useless for rerouting purposes. You may have to set `<CODE>no
envelope</CODE>' to prevent fetchmail from being bamboozled by this.<p>
Check also answer <a href="#T1">T1</a> on a reliable way to do multidrop
delivery if your ISP (or your mail redirection provider) is using qmail.<p>
<hr>
<h2><a name="M3">M3. I tried to run a mailing list using multidrop, and I have a mail loop!</a></h2>
This isn't fetchmail's fault. Check your mailing list. If the list
expansion includes yourself or anybody else at your mailserver (that is, not on
the client side) you've created a mail loop. Just chop the host part off any
local addresses in the list.<p>
If you use sendmail, you can check the list expansion with
<CODE>sendmail -bv</CODE>.<p>
<hr>
<h2><a name="M4">M4. My multidrop fetchmail seems to be having DNS problems.</a></h2>
We have one report from a Linux user (not the same one as in <a
href="#R1">R1</a>!) who solved this problem by removing the reference
to -lresolv from his link line and relinking. Apparently in some
older Linux distributions the libc5 bind library version works
better.<p>
As of 2.2, the configure script has been hacked so the bind library is linked
only if it is actually needed. So under Linux it won't be, and this problem
should go away.<p>
<hr>
<h2><a name="M5">M5. I'm seeing long DNS delays before each message is processed.</a></h2>
Use the `<CODE>aka</CODE>' option to pre-declare as many of your
mailserver's DNS names as you can. When an address's host part
matches an aka name, no DNS lookup needs to be done to check it.<p>
If you're sure you've pre-declared all of your mailserver's DNS names,
you can use the `<CODE>no dns</CODE>' option to prevent other hostname
parts from being looked up at all.<p>
Sometimes delays are unavoidable. Some SMTP listeners try to call DNS
on the From-address hostname as a way of checking that the address is valid.<p>
<hr>
<h2><a name="M6">M6. How do I get multidrop mode to work with majordomo?</a></h2>
In order for sendmail to execute the command strings in the majordomo
alias file, it is necessary for sendmail to think that the mail it
receives via SMTP really is destined for a local user name. A normal
virtual-domain setup results in delivery to the default mailbox,
rather than expansion through majordomo.<P>
Michael <michael@bizsystems.com> gave us a recipe for dealing
with this case that pairs a run control file like this:<P>
<pre>
poll your.pop3.server proto pop3:
no envelope no dns
localdomains virtual.localdomain1.com virtual.localdomain2.com ...
user yourISPusername is root * here,
password yourISPpassword fetchall
</pre>
with a hack on your local sendmail.cf like this:<P>
<pre>
#############################################
# virtual info, local hack for ruleset 98 #
#############################################
# domains to treat as direct mapped local domain
CVvirtual.localdomain1.com virtual.localdomain2.com ...
---------------------------
in ruleset 98 add
-------------------------
# handle virtual users
R$+ <@ $=V . > $: $1 < @ $j . >
R< @ > $+ < @ $=V . > $: $1 < @ $j . >
R< @ > $+ $: $1
R< error : $- $+ > $* $#error $@ $1 $: $2
R< $+ > $+ < @ $+ > $: $>97 $1
</pre>
This ruleset just strips virtual domain names off the addresses of incoming
mail. Your sendmail must be 8.8 or newer for this to work. Michael
says:<P>
<BLOCKQUOTE>
I use this scheme with 2 virtual domains and the default ISP
user+domain and service about 30 mail accounts + majordomo on my
inside pop3 server with fetchmail and sendmail 8.83
</BLOCKQUOTE>
<hr>
<h2><a name="M7">M7. Multidrop mode isn't parsing envelope addresses from
my Received headers as it should.</a></h2>
It may happen that you're getting what appear to be well-formed
sendmail Received headers, but fetchmail can't seem to extract an
envelope address from them. There can be a couple of reasons for
this.<P>
<h3>Spurious Received lines need to be skipped:</h3>
First, fetchmail might be looking at the wrong Received header.
Normally it looks only on the first one it sees, on the theory that
that one was last added and is going to be the one containing your
mailserver's theory of who the message was addressed to.<P>
Some (unusual) mailserver configurations will generate extra Received
lines which you need to skip. To arrange this, use the optional
skip prefix argument of the `envelope' option; you may need to say
something like `<code>envelope 1 Received</code>' or `<code>envelope 2
Received</code>'.
<h3>The `by' clause doesn't contain a mailserver alias:</h3>
When fetchmail parses a Received line that looks like
<pre>
Received: from send103.yahoomail.com (send103.yahoomail.com [205.180.60.92])
by iserv.ttns.net (8.8.5/8.8.5) with SMTP id RAA10088
for <ksturgeon@fbceg.org>; Wed, 9 Sep 1998 17:01:59 -0700
</pre>
it checks to see if `iserv.ttns.net' is a DNS alias of your mailserver
before accepting `ksturgeon@fbceg.org' as an envelope address. This
check might fail if your DNS were misconfigured, or if you were using `no dns'
and had failed to declare iserv.ttns.net as an alias of your server.<P>
<hr>
<h2><a name="M8">M8. Users are getting multiple copies of messages.</a></h2>
It's a consequence of multidrop. What's happening is that you have
N users subscribed to the same list. The list software sends N
copies, not knowing they will end up in the same multidrop box. Since
they are both locally addressed to all N users, fetchmail delivers N
copies to each user.<P>
Fetchmail tries to eliminate adjacent duplicate messages in a
multidrop mailbox. However, this logic depends on the message-ID
being identical in both copies. It also depends on the two copies
being adjacent in the server mailbox. The former is usually the case,
but the latter condition sometimes fails in a timing-dependent way if
the server was processing multiple incoming mail streams.
I could eliminate this problem by keeping a list of all message-IDs
received during a poll so far and dropping any message that matches a
seen mail ID. The touble is that this is an O(N**2) operation that
might significantly slow down the retriweval of large mail batches.<P>
<hr>
<h2><a name="X1">X1. Spurious blank lines are appearing in the headers of fetched mail.</a></h2>
What's probably happening is that the POP/IMAP daemon on your
mailserver is inserting a non-RFC822 header (like X-POP3-Rcpt:) and
something in your delivery path (most likely an old version of the
<em>deliver</em> program, which sendmail often calls to do local delivery) is
failing to recognize it as a header.<p>
This is not fetchmail's problem. The first thing to try is installing
a current version of <em>deliver</em>. If this doesn't work, try to
figure out which other program in your mail path is inserting the
blank line and replace that. If you can't do either of these things,
pick a different MDA (such as procmail) and declare it with the
`<CODE>mda</CODE>' option.<p>
<hr>
<h2><a name="X2">X2. My mail client can't see a Subject line.</a></h2>
First, see <a href="#X1">X1</a>. This is quite probably the same
problem (X-POP3-Rcpt header or something similar being inserted by
the server and choked on by an old version of <em>deliver</em>).<p>
The O'Reilly sendmail book does warn that IDA sendmail doesn't process
X- headers correctly. If this is your problem, all I can suggest is
replacing IDA sendmail, because it's broken and not RFC822 conformant.<p>
<hr>
<h2><a name="X3">X3. Messages containing "From" at start of line are being split.</a></h2>
If you know the messages aren't split in your server mailbox, then this
is a problem with your POP/IMAP server, your client-side SMTP listener or
your local delivery agent. Fetchmail cannot split messages.<p>
Some POP server daemons ignore Content-Length headers and split messages on
From lines. We have one report that the 2.1 version of the BSD popper
program (as distributed on Solaris 2.5 and elsewhere) is broken this way.<p>
You can test this. Declare an mda of `cat' and send yourself one
piece of mail containing "From" at start of a line. If you see a
split message, your POP/IMAP server is at fault. Upgrade to a more
recent version.<p>
Sendmail and other SMTP listeners don't split RFC822 messages either.
What's probably happening is either sendmail's local delivery agent or
your mail reader are not quite RFC822-conformant and are breaking
messages on what it thinks are Unix-style From headers. You can
figure out which by looking at your client-side mailbox with vi or
more. If the message is already split in your mailbox, your local
delivery agent is the problem. If it's not, your mailreader is the
problem.<p>
If you can't replace the offending program, take a look at your
sendmail.cf file. There will likely be a line something like<p>
<pre>
Mlocal, P=/usr/bin/procmail, F=lsDFMShP, S=10, R=20/40, A=procmail -Y -d $u
</pre>
describing your local delivery agent. Try inserting the `E' option in the
flags part (the F= string). This will make sendmail turn each dangerous
start-of-line From into a >From, preventing programs further downstream
from acting up.<p>
<hr>
<h2><a name="X4">X4.</a><a name="generic_mangling">My mail is being mangled in a new and different way</a></h2>
The first thing you need to do is pin down what program is doing the
mangling. We don't like getting bug reports about fetchmail that are
actually due to some other program's malfeasance, so please go through
this diagnostic sequence before sending us a complaint.<P>
There are five possible culprits to consider, listed here in the order
they pass your mail:<P>
<ol>
<li> Programs upstream of your server mailbox.
<li> The POP or IMAP server on your mailserver host.
<li> The fetchmail program itself.
<li> Your local sendmail.
<li> Your LDA (local delivery agent), as called by sendmail or
specified by <code>mda</CODE>.
</ol>
Often it happens that fetchmail itself is OK, but using it exposes
pre-existing bugs in your downstream software, or your downstream
software has a bad interaction with POP/IMAP. You need to pin down
exactly where the message is being garbled in order to deduce what is
actually going on.<P>
The first thing to do is send yourself a test message, and retrieve it
with a .fetchmailrc entry containing the following (or by running with
the equivalent command-line options):<P>
<pre>
mda "cat >MBOX" keep fetchall
</pre>
This will capture what fetchmail gets from the server, except for (a)
the extra Received header line fetchmail prepends, (b) header address
changes due to <code>rewrite</code>, and (c) any end-of-line changes
due to the <code>forcecr</code> and <code>stripcr</code> options.
MBOX will in fact contain what programs downstream of fetchmail
see.<P>
The most common causes of mangling are bugs and misconfigurations in
those downstream programs. If MBOX looks unmangled, you will know
that is what is going on and that it is not fetchmail's problem. Take
a look at the other FAQ items in this section for possible clues about
how to fix your problem.<P>
If MBOX looks mangled, the next thing to do is compare it with your
actual server mailbox (if possible). That's why you specified
<code>keep</code>, so the server copy would not be deleted. If your
server mailbox looks mangled, programs upstream of your server mailbox
are at fault. Unfortunately there is probably little you can do about
this aside from complaining to your site postmaster, and nothing at
all fetchmail can do about it!<P>
More likely you'll find that the server copy looks OK. In that case
either the POP/IMAP server or fetchmail is doing the mangling. To
determine which, you'll need to telnet to the server port and simulate
a fetchmail session yourself. This is not actually hard (both POP3
and IMAP are simple, text-only, line-oriented protocols) but requires
some attention to detail. You should be able to use a fetchmail -v
log as a model for a session, but remember that the "*" in your LOGIN
or PASS command dump has to be replaced with your actual password.<P>
The objective of manually simulating fetchmail is so you can see
exactly what fetchmail sees. If you see a mangled message, then your
server is at fault, and you probably need to complain to your
mailserver administrators. However, we like to know what the broken
servers are so we can warn people away from them. So please send
us a transcript of the session including the mangling <em>and the
server's initial greeting line</em>. Please tell us anything else
you think might be useful about the server, like the server host's
operating system.<P>
If your manual fetchmail simulation shows an unmangled message,
congratulations. You've found an actual fetchmail bug, which is a
pretty rare thing these days. Complain to us and we'll fix it.
Please include the session transcript of your manual fetchmail
simulation along with the other things described in the FAQ entry on
<a href="#G3">reporting bugs</a>.
<hr>
<h2><a name="X5">X5. Using POP3, retrievals seems to be fetching too much!</a></h2>
This may happen in versions of fetchmail after 4.4.1 and before 4.4.8.
Versions after 4.4.1 use POP3's TOP command rather than RETR, in order
to avoid marking the message seen (leaving it unseen is helpful for
later recovery if you lose your connection in the middle of a
retrieval).<P>
Versions of fetchmail from 4.4.2 through 4.4.7 had a bad interaction
with Eudora qpopper versions 2.3 and later. The TOP bounds check was
fooled by an overflow condition in the TOP argument. Decrementing the
TOP argument in 4.4.7 fixed this.<P>
Fix: Upgrade to a later version of fetchmail.<P>
Workaround: set the <code>fetchall</code> option. Under POP3
this has the side effect of forcing RETR use.<P>
<hr>
<h2><a name="X6">X6. My mail attachments are being dropped or mangled.</a></h2>
This isn't fetchmail's doing -- fetchmail never drops lines in message
bodies or attachments. It may be your POP server, or it may be the
sender's mail user agent (or a bad combination of both).<p>
The Mail Max POP3 server and the InterChange and Imail IMAP servers
are known to simply drop MIME attachments when uploading messages.
We've had sporadic reports of problems with Microsoft Exchange and
Outlook servers. Windows- and NT-based POP servers seem especially
prone to mangle attachments. If you are running one of these,
replacing your server with a Unix machine is probably the only
effective solution.<p>
We've also had a report that Lotus Notes sometimes trashes the
MIME type of messages. In particular, it seems to modify MIME
headers introducing type application/pdf, mangling the type
to application/octet-stream. It may corrupt other MIME types
as well.<p>
The IMAP service of Lotus Domino has a known bug in the way it
generates MIME Content-type headers (observed on Lotus Domino 5.0.2b).
It's a subtle one that doesn't show up when Netscape Messenger and
other clients use a FETCH BODY[] to grab the whole message. When
fetchmail uses FETCH RFC822.HEADER and FETCH RFC822.TEXT to get first
the header and then the body, Domino generates different Boundary tags
for each part, .e.g. one tag is declared in the Content-type header and
another is used to separate the MIME parts in the body. This doesn't
work. (I have heard a rumor that this bug is scheduled to be fixed
in Domino release 6; you can find a workaround at contrib/domino.)<p>
Another rich source of attachment problems is Microsoft Exchange and
Microsoft Outlook. If you see unreadable attachments with a
ContentType of "application/x-tnef", you're having this problem. The
<a href="http://world.std.com/~damned/software.html">TNEF</a> utility
may help.<p>
Rob Funk explains: Unfortunately there also remain many mail user
agents that don't write correct MIME messages. One big offender is Sun
MailTool attachments, which are formatted enough like MIME that some
programs could get confused; these are generated by the mailtool and
dtmail programs (the mail programs in Sun's OpenWindows and CDE
environments).<p>
One solution to problems related to misformatted MIME attachments is
the <a href="ftp://ftp.uu.se/pub/unix/networking/mail/emil/">emil</a>
program; see its <a
href="ftp://ftp.uu.se/pub/unix/networking/mail/emil/TUTORIAL.html">tutorial</a>
file at that site for details on emil. It is useful for
converting character sets, attachment encodings, and attachment
formats. At this writing, emil does not appear to have been
maintained since a patch to version 2.1.0beta9 in late 1997, but it is
still useful.<p>
One good way of using emil is from within procmail. You can have
procmail look for signs of problematic message formatting, and pipe
those messages through emil to be fixed. emil will not always be able
to fix the problem, in which case the message is unchanged.<p>
A possible rule to be inserted into a .procmailrc file for using emil
would be:
<pre>
:0HB
* 1^1 ^Content-Type: \/X-sun[^;]*
* 1^1 ^Content-Type: \/application/mac-binhex[^;]*
* 1^1 ^Content-Transfer-Encoding: \/x-binhex[^;]*
* 1^1 ^Content-Transfer-Encoding: \/x-uuencode[^;]*
{
LOG="Converting $MATCH
"
:0fw
| emil -A B -T Q -B BA -C iso-8859-1 -H Q -F MIME \
| gawk '{gsub(/\r\n?/,"\n");print $0}'
}
</pre>
The "1^1" in the conditions is a way of specifying to procmail that if
any one of the four listed expressions is found in the message, the
total condition is considered true, and the message gets passed into
emil. These four subconditions check whether the message has a Sun
attachment, a binhex attachment, or a uuencoded attachment; there are
others that could be added to check these things better and to check
other relevant conditions. The "LOG=" line writes a line into the
procmail log; the lone double-quote beginning the following line makes
sure the log entry gets an end-of-line character. The call to gawk
(GNU awk) is for fixing end-of-line conventions, since emil sometimes
leaves those in the format of the originating machine; it could
probably be replaced with a sed subsitution.<p>
The emil call itself tries to ensure that the message uses:
<ul>
<li> BinHex encoding for any Apple Macintosh-only attachments
<li> Quoted-Printable encoding for text (when necessary)
<li> Base64 Encoding for binary attachments
<li> iso-8859-1 character set for text (unfortunately emil can't yet
convert from windows-1252 to iso-8859-1)
<li> Quoted-Printable encoding for headers
<li> MIME attachment format
</ul>
Most of these (the primary exceptions being the character set and the
Apple binary format) are as they should be for good internet
interoperability.<p>
Some mail servers (Lotus Domino is a suspect here) mangle
Sun-formatted messages, so the conversion to MIME needs to happen
before such programs see the message. The ideal is to rid the world
of Sun-formatted messages: don't use mailtool for sending attachments
(it doesn't understand MIME anyway, and most of the world doesn't
understand its attachments, so it really shouldn't be used at all),
and make sure dtmail is set to use MIME rather than mailtool's format.<p>
<hr>
<h2><a name="X7">X7. Some mail attachments are hanging fetchmail.</a></h2>
This isn't fetchmail's problem either; fetchmail doesn't know anything
about mail attachments and doesn't treat them any differently from
plain message data.<P>
The most usual cause of this problem seems to be bugs in your network
transport layer's capability to handle the very large TCP/IP packets
that attachments tend to turn into. You can test this theory by trying to
download the offending message through a webmail account; using HTTP
for the message tends to simulate large-packet stress rather well, and
you will probably find that the messages that seem to be choking
fetchmail will make your HTTP download speed drop to zero.<P>
This problem can be caused by subtle bugs in the packet-reassembly
layer of your TCP/IP stack; these often don't manifest at normal
packet sizes. It may also be caused by malfunctioning path-MTU
discovery on the mailserver. Or, if there's a modem in the link,
it may be because the attachment contains the Hayes mode escape "+++".
<hr>
<h2><a name="O1">O1. The --logfile option doesn't work if the logfile doesn't exist.</a></h2>
This is a feature, not a bug. It's in line with normal practice for
system daemons and allows you to suppress logging by removing the log,
without hacking potentially fragile startup scripts. To get around
it, just touch(1) the logfile before you run fetchmail (this will have
no effect on the contents of the logfile if it already exists).<P>
<hr>
<h2><a name="O2">O2. Every time I get a POP or IMAP message the header
is dumped to all my terminal sessions.</a></h2>
Fetchmail uses the local sendmail to perform final delivery, which
Netscape and other clients doesn't do; the announcement of new messages
is done by a daemon that sendmail pokes. There should be a ``biff''
command to control this. Type
<PRE>
biff n
</PRE>
to turn it off. If this doesn't work, try the command
<PRE>
chmod -x `tty`
</PRE>
which is essentially what <code>biff -n</code> will do. If this
doesn't work, comment out any reference to ``comsat'' in your
/etc/inetd.conf file and restart inetd.<P>
In Slackware Linux distributions, the last line in /etc/profile is
<PRE>
biff y
</PRE>
Change this to
<PRE>
biff n
</PRE>
to solve the problem system-wide.<P>
<hr>
<h2><a name="O3">O3. Does fetchmail reread its rc file every poll cycle?</a></h2>
No, but versions 5.2.2 and later will notice when you modify your rc
file and restart, reading it.
<hr>
<h2><a name="O4">O4. Why do deleted messages show up again when I take
a line hit while downloading?</a></h2>
Because you're using a POP3 other than Qualcomm qpopper, or an IMAP
with a long expunge interval.<P>
According to the POP3 RFCs, deletes aren't actually performed until
you issue the end-of-session QUIT command. Fetchmail cannot fix this,
because doing it right takes cooperation from the server. There are
two possible remedies:<P>
One is to switch to qpopper (the free POP3 server from Qualcomm,
the Eudora people). The qpopper software violates the POP3 RFCs by
doing an expunge (removing deleted messages) on a line hangup, as well
as on processing a QUIT command.<P>
The other (which we recommend) is to switch to <a
href="http://www.imap.org">IMAP</a>. IMAP has an explicit expunge
command and fetchmail normally uses it to delete messages immediately
after they are downloaded.<P>
If you get very unlucky, you might take a line hit in the window
between the delete and the expunge. If you've set a longer expunge
interval, the window gets wider. This problem should correct itself
the next time you complete a successful query.<P>
<hr>
<h2><a name="O5">O5. Why is fetched mail being logged with my name, not the real From address?</a></h2>
Because logging is done based on the address indicated by the sending
SMTP's MAIL FROM, and some listeners are picky about that address.<p>
Some SMTP listeners get upset if you try to hand them a MAIL FROM
address naming a different host than the originating site for your
connection. This is a feature, not a bug -- it's supposed to help
prevent people from forging mail with a bogus origin site. (RFC 1123
says you shouldn't do this exclusion...)<p>
Since the originating site of a fetchmail delivery connection is
localhost, this effectively means these picky listeners will barf on
any MAIL FROM address fetchmail hands them with an @ in it!<p>
Versions 2.1 and up try the header From address first and fall back to
the calling-user ID. So if your SMTP listener isn't picky, the log
will look right.<p>
<hr>
<h2><a name="O6">O6. I'm seeing long sendmail delays or hangs near the start of each poll cycle.</a></h2>
Sendmail does a hostname lookup when it first starts up, and also each
time it gets a HELO in listener mode.<p>
Your resolver configuration may be causing one of these lookups to
fail and time out. Check <code>/etc/resolv.conf</code> and
<code>/etc/hosts</code> file. Make sure your hostname and
fully-qualified domain name are both in <code>/etc/hosts</code>, and
that hosts is looked at before DNS is queried. You probably also want
your remote mail server(s) to be in the hosts file.<p>
You can suppress the startup-time lookup if need to by reconfiguring
with <code>FEATURE(nodns)</code>.<p>
Configuring your bind library to cache DNS lookups locally may help,
and is a good idea for speeding up other services as well. Switching to
a faster MTA like qmail or exim might help. <p>
<hr>
<h2><a name="O7">O7. Why doesn't fetchmail deliver mail in date-sorted order?</a></h2>
Because that's not the order the server hands it to fetchmail in.<P>
Fetchmail getting mail from a POP server delivers mail in the order
that your server delivers mail. Fetchmail can't do anything about
this; it's a limitation of the underlying POP protocol.<P>
In theory it might be possible for fetchmail in IMAP mode to sort
messages by date, but this would be in violation of two basics of
fetchmail's design philosophy: (a) to be as simple and transparent a
pipe as possible, and (b) to <em>hide</em>, rather than emphasize, the
differences between the remote-fetch protocols it uses.<P>
Re-ordering messages is a user-agent function, anyway.<P>
<hr>
<h2><a name="O8">O8. I'm using pppd. Why isn't my monitor option working?</a></h2>
There is a combination of circumstances that can confuse fetchmail.
If you have set up demand dialing with pppd, and pppd has an idle
timeout, and you have lcp-echo-interval set, then the
lcp-echo-interval time must be longer than the pppd idle timeout.
Otherwise it is going keep increasing the packet counters that fetchmail
relies upon, triggering fetchmail into polling after its own delay
interval and thus preventing the pppd link from ever reaching its
inactivity timeout.<p>
<hr>
<h2><a name="O9">O9. Why does fetchmail keep retrieving the same messages
over and over?</a></h2>
First, check to see that you haven't enabled the <cite>keep</cite>
and <cite>fetchall</cite> option. If you have, turn <cite>keep</cite> off.<p>
There are various forms of lossage involving the POP3 UIDL feature
that can lead to all your old messages being seen again after a line
drop. I have given up trying to fix these, as the UIDL code breaks
worse every time I touch it. The problem is fundamental; maintaining
and garbage-collecting the right kind of client-side state is just
hard. Whoever put UIDLs in RFC1725 and removed LAST should be hung
up by his thumbs and whipped with scorpions. The right answers are
either (a) live with the occasional breakage, (b) switch to IMAP4,
or (c) fix the code yourself and send me a patch. Unless you choose
(c), I don't want to hear about it.<p>
This can also happen when some other mail client is logged in to your
mail server, if it uses a simple exclusive-locking scheme (and many,
especially most POP3 servers, do exactly that). Your fetchmail is
able to retrieve the messages, but because the mailbox is write-locked
by the other instance yours can neither mark messages seen or delete them.
The solution is to either (a) wait for the other client to finish, or (b)
terminate it.<p>
James Stevens <James.Stevens@kyzo.com> writes:<p>
<em>
We had a Linux box dialing the Net and collecting mail from an NT POP3
server. Fetchmail was correctly collecting and deleting each e-mail
one by one. However,the dial-up connection was very unreliable and
would often just drop out in the middle of a session.<p>
Interestingly, unless the TCP POP3 connection was terminated normally
(I guess with a POP3 "QUIT" command) NT would then roll back all the
deletes !!!<p>
This meant if the first e-mail was very large it might just end up
continuously collecting it, basically jamming the queue. Or, if the
queue became very full itmight never get a long enough phone
connection to retrieve the entire mailbox, and NT would roll back any
deletes, so it would end up collecting (and delivering) the first few
e-mails again and again. As the POP3 mailbox became fuller and fuller
the chances of getting a connection long enough to collect theentire
mailbox became smaller and smaller.<p>
Our solution was to make fetchmail only collect a few (say 5 or 10)
e-mails at atime, thus trying to ensure that the POP3 connection is
terminated correctly.
</em>
That's one solution. Perhaps a better one would be to FORMAT C: and
install Linux on your server...<p>
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<P><ADDRESS>Eric S. Raymond <A HREF="mailto:esr@thyrsus.com"><esr@snark.thyrsus.com></A></ADDRESS>
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