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Before reporting any bug, please read G3 for advice on how to include diagnostic information that will get your bug fixed as quickly as possible.
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 esr@thyrsus.com.
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.
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.
Fetchmail is open-source 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.
Fetchmail is licensed under the GNU General Public License.
If you found this FAQ in the distribution, see the README for fetchmail's full feature list.
The latest HTML FAQ is available alongside the latest fetchmail sources at the fetchmail home page: http://www.tuxedo.org/~esr/fetchmail. You can also usually find both in the POP mail tools directory on Sunsite.
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.
Yes I will, provided you include enough diagnostic information for me to go on. Send bugs to fetchmail-friends. When reporting bugs, please include the following:
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.
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 before sending in a bug report.
If your bug is something that used to work but stopped working when you upgraded, then you can help pin the bug down by trying intermediate versions of fetchmail until you identify the revision that broke your feature. The smart way to do this is by binary search on the version sequence. First, try the version halfway between your last good one and the current one. If it works, the failure was introduced in the upper half of the sequence; if it doesn't, the failure was introduced in the lower half. Now bisect that half in the same way. In a very few tries, you should be able to identify the exact adjacent pair of versions between which your bug was introduced -- and with information like that, I can usually come up with a fix very quickly.
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.
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!
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 X before submitting a bug report. Pay special attention to the item on diagnosing mail mangling. 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.
A transcript of the failed session with -v -v (yes, that's two -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.
If you upgraded your fetchmail and something broke, you should include session transcripts with -v -v of both the working and failing versions. Very often, the source of the problem can instantly identified by looking at the differences in protocol transactions.
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:
CFLAGS=-g LDFLAGS=" " ./configureand then rebuild in order to generate a version that can be gdb-traced.
Best of all is a mail file which, when fetched, will reproduce the bug under the latest (current) version.
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 necessary that you give me a way to reproduce it.
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
mda 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.
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.
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 design notes.
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.
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.
There is a fetchmail-friends list (fetchmail-friends@lists.ccil.org) for people who want to discuss fixes and improvements in fetchmail and help co-develop it. It's a MailMan list, which you can sign up for at http://lists.ccil.org/mailman/listinfo/fetchmail-friends. There is also an announcements-only list, fetchmail-announce@lists.ccil.org, which you can sign up for at http://lists.ccil.org/mailman/listinfo/fetchmail-announce.
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.
The experiment was a success. I wrote a paper about it titled The Cathedral and the Bazaar 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 give away the source for Netscape Communicator.
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.
The short answer: IMAP 2000 running over Unix.
Here's a longer answer:
Fetchmail will work with any POP, IMAP, ETRN, or ODMR server that conforms to the relevant RFCs (and even some outright broken ones like Microsoft Exchange and Novell GroupWise). 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.
Most modern Unixes (and effectively all Linux/*BSD systems) come with POP3 support preconfigured (but beware of the horribly broken POP3 server mentioned in D2). 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).
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. The new IMAP 2000 is particularly nice, as it supports CRAM-MD5 so you don't have to ship your mail password over the net en clair (fetchmail autodetects this capability). Older versions had support for GSSAPI giving a similar effect, .
Don't be fooled by NT/Exchange propaganda. M$ Exchange is just plain broken (see item S2) 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 white paper on Unix vs. NT performance.
Source for a high-quality supported implementation of POP is available from the Eudora FTP site. 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.
Fetchmail will work with all popular mail transport programs. 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 -- elm, pine, mh, or mutt -- will work fine with fetchmail.
All this having been said, I can't resist putting in a discreet plug for mutt. 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 :-).
Depending on what your mail server you are talking to, this ranges from trivial to impossible. It may even be next to useless.
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.
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).
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 K3.
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 GPG (Gnu Privacy Guard) or PGP (Pretty Good Privacy).
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.
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 fetchmail -v
to see these, or telnet direct to the server port (110 for POP3, 143 for
IMAP).
If your mailserver is using IMAP 2000, you'll have CRAM-MD5 support built in. Fetchmail autodetects this; you can skip the rest of this section.
The POP3 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 popauth(8) 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.
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.
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 and POP3 facility described by RFC1731 and RFC1734. You can tell if this one is present by looking for AUTH=KERBEROS_V4 in the CAPABILITY response.
If you are fetching mail from a CompuServe POP3 account, you can use their RPA authentication (which works much like APOP). See S3 for details. If you are fetching mail from Microsoft Exchange using IMAP, you will be able to use NTLM.
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 Craig Metz). 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.
You can get both POP3 and IMAP OTP patches from Craig Metz at http://www.inner.net/pub/.
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 ;-)
Finally, you can use SSL for complete end-to-end encryption if you have an SSL-enabled mailserver.
Yes. In order to avoid giving indigestion to certain picky MTAs (notably exim), 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).
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.
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!
Use the smtpaddress option to force the appended hostname
to one with a (fixed) IP address of 127.0.0.1 in your
/etc/hosts. (The name `localhost' will usually work; or
you can use the IP address itself).
Only one fetchmail option interacts directly with your IP address,
`interface'. 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 C3.
I recommend against trying to set up the interface 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 interface option (if you need one) later.
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.
You can use On-Demand Mail Relay (ODMR) with a dynamic IP address; that's what it was designed for, and it provides capabilities very similar to ETRN. Unfortunately ODMR servers are not yet widely deployed, as of early 2001.
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
DMsmarthost.herein your
sendmail.cf will work, or you can set
MASQUERADE_AS(smarthost.here)in the m4 configuration and do a reconfigure. (In both cases, replace
smarthost.here with the actual name of your mailhost.)
See the sendmail
FAQ for more details.
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 SOCKS distribution site.
The specific recipe for using fetchmail with a firewall is at K1
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?
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.
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.
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.
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.
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.
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.
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).
The vendor-supplied make on FreeBSD systems can only be used within FreeBSD's "scope", e.g. the ports collection. Type "gmake" to run GNU make and better things will happen.
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 flex and use that. All will be happier.''
I couldn't have put it better myself, and ain't going to try now.
(The same problem has been reported under HP-UX v10.20 and IRIX)
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 1then you must add "-lresolv" to the LOADLIBS line in your Makefile once you have installed the `bind' package.
If you get link errors involving dcgettext, like this:
rcfile_y.o: In function `yyparse': rcfile_y.o(.text+0x3aa): undefined reference to `dcgettext__' rcfile_y.o(.text+0x4f2): undefined reference to `dcgettext__' rcfile_y.o(.text+0x5ee): undefined reference to `dcgettext__' rcfile_y.o: In function `yyerror': rcfile_y.o(.text+0xc7c): undefined reference to `dcgettext__' rcfile_y.o(.text+0xcc8): undefined reference to `dcgettext__' rcfile_y.o(.text+0xdf9): more undefined references to `dcgettext__' followreconfigure with configure --with-included-gettext. This is due to some brain-damage in the GNU internationalization libraries.
If you were using ETRN mode, change your smtphost option to a fetchdomains option.
The `via localhost' special case for use with ssh tunnelling is gone. Use the %h feature of plugin instead.
In 5.6.8, the preauth keyword and option were changed back to auth. The preauth synonym will still be supported through a few more point releases.
When trying to identify you to an IMAP or POP mailserver, fetchmail now first tries methods that don't require a password (GSSAPI, KERBEROS_IV); then it looks for methods that mask your password (CRAM-MD5, X-OTP); and only if it the server doesn't support any of those will it ship your password en clair.
Setting the preauth option to any value other than `password' will prevent from looking for a password in your .netrc file or querying for it at startup time.
dns 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.
via' option was introduced, I realized
that the interactions between the `via',
`aka', and `localdomains' 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.
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
`poll' or `skip' keyword being still
interpreted as a DNS name for address-matching purposes, even in the
presence of a `via' option, will break.
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.
remote' keyword has been changed to `folder'.
If you try to use the old keyword, the parser will utter a warning.
username'
keyword leading the first user entry attached to a server entry.
This error can be triggered by having a user option such as `keep'
or `fetchall' before the first explicit username. For
example, if you write
poll openmail protocol pop3 keep user "Hal DeVore" there is hdevore herethe `
keep' option will generate an entire user entry with
the default username (the name of fetchmail's invoking user).
The popclient compatibility syntax was removed in 4.0. It complicated the configuration file grammar and confused users.
interface', `monitor' and
`batchlimit' options changed after 2.8.
They used to be global options with `set' syntax like the
batchlimit and logfile options. Now they're per-server options, like
`protocol'.
If you had something like
set interface = "sl0/10.0.2.15"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.
Do similarly for any `monitor' or `batchlimit' options.
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.
The lexical analyzer in 5.0.6 and beyond is smarter and assumes any token following "username" or "password" is a string.
Upgrade to a 5.0.6 or later fetchmail, or put string quotes around your token.
Yes, I know these ordering restrictions are hard to understand. Unfortunately, they're necessary in order to allow the `defaults' feature to work.
On the machine where I'm the only real user, I run fetchmail as root from a cron job, like this:
fetchmail -u "itz" -p POP3 -s bolero.rahul.net
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:
skip bolero.rahul.net proto POP3
user itz is itz
It won't work if the second line is just "user itz". This is silly.
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.
Answer:
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.
"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.
One: it's not always possible. Suppose you have an SMTP host declared that's not the machine fetchmail is running on? You lose.
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.).
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.
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.
Some people start up and shut down fetchmail using the ppp-up and ppp-down scripts of pppd.
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.
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.
To determine the device:
interface "sl0/205.164.136.0/255.255.255.0"would work. To range over any value of the last two octets (65536 addresses) you would use
interface "sl0/205.164.0.0/255.255.0.0"
Stock sendmails can now do anti-spam exclusions based on a database of filter rules. The human-readable form of the database is at /etc/mail/access. The database itself is at /etc/mail/access.db.
The table itself uses email addresses, domain names, and network numbers as keys. For example,
spammer@aol.com REJECT cyberspammer.com REJECT 192.168.212 REJECT
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 sendmail documentation for details)
To actually set up the database, runmakemap hash deny <denyin /etc/mail.
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.
Under no circumstances put your mailhost or any host you accept mail from using fetchmail into your reject file. You will lose mail if you do this!!!
poll mainsite.example.com proto pop3 user .... poll secondary.example.com proto pop3 interval 6 user ...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.
Pick a location (such as /etc/fetchmailrc) and use fetchmail's -f option to point fetchmail at it. That should solve the problem.
smtphost or smtpname option.
See the manual page for details.
FEATURE(always_add_domain) is included
in sendmail's configuration, you can leave the rewrite
option off.
If your sendmail complains ``sendmail does not relay'', make sure
your sendmail.cf file says Cwlocalhost
so that sendmail recognizes `localhost' as a name of its host.
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/)
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
FEATURE(accept_unqualified_senders).
Günther Leber reports that Digital Unix sendmails won't work with
fetchmail. The symptom is an error message "553 Local configuration
error, hostname not recognized as local". 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 --invisible mode.
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:
H?l?Delivered-To: $hThis 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:
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 $hFor both hacks, you have to declare `
envelope "Delivered-To:"' 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 `domain.com local:local-pop-user' for the first and
`domain.com mdrop:local-pop-user' for the second hack to your
mailertable.
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.
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.
forcecr option; qmail's listener mode doesn't like
header or message lines terminated with bare linefeeds.
(This information is thanks to Robert de Bath <robert@mayday.cix.co.uk>.)
If a mailhost is using the qmail package (see http://pobox.com/~djb/qmail.html) 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.
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.
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:
Delivered-To: mbox-userstr-username@userhost.userdom.dom.com
A single host maildrop will be slightly simpler:
Delivered-To: mbox-userstr-username@userhost.dom.com
The ISP can make the 'mbox-userstr-' prefix anything they choose
but a string matching the user host name is likely.
To use this line you must:
| ../bin/qmail-inject -a -f"$SENDER" "${LOCAL#mbox-userstr-}@$HOST"
Note this does require a modern /bin/sh.
Peter Wilson adds:
``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).''
Luca Olivetti adds:
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 `qvirtual
"mbox-userstr-"' in your fetchmail config file to strip the prefix
from the local user name.
If you have rewrite on:
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.
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:
local_domains = thyrsus.com:localhost
If you have rewrite off:
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 rewrite 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.
The right way to fix this is to enable the rewrite 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.
If you must run with rewrite 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
sender_unqualified_hosts = localhost
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).
Smail 3.2 is very nearly plug-compatible with sendmail, and may work fine out of the box.
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.
Very recent smail versions require an -smtp_hello_verify
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 must allow this
mismatch, so smail's new behavior (introduced sometime between
3.2.0.90 and 3.2.0.95) is a bug.
You may also need to say
-smtp_hello_broken_allow=127.0.0.1
in order for smail to accept the "localhost" that fetchmail normally
appends to recipient addresses.
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 MMDF recipe that describes replacing a UUCP link with fetchmail feeding MMDF.
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'. T7. How can I use fetchmail with Courier IMAP?
The courier mta doesn't like RCPT addresses that look like
someone@localhost. Work around this with an
smtphost or smtpaddress.
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 upgrading to qpopper 3.0b1.
It's been reliably reported that Exchange 2000's POP3 support is so broken that it's unusable. One symptom is that messages without a terminating newline get the POP3 message termination dot emitted -- you guessed it -- right after the last character of the message, with no terminating newline added. This will hang fetchmail or any other RFC-compliant server. IMAP is alleged to work OK, though.
Older versions of Exchange are semi-usable.
Fetchmail using IMAP supports the proprietary NTLM mode used with M$ Exchange servers. To enable this, configure fetchmail with the --enable-NTLM option and recompile it. 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.
M$ Exchange violates the POP3 and IMAP 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).
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).
Somewhat belatedly, I've learned that there's supposed to be a registry bit that can fix this breakage:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MsExchangeIs\Parameters System\Pop3 CompatibilityThis is a bitmask that controls the variations from the standard protocol. The bits defined are:
KEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MsExchangeIs\Parameters System\Pop3 Performance
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.
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.
You've got several options:
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.
I'll provide the CD.
fetchmail -V;
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).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.
Warning: the debug (-v -v) output of fetchmail will show your pass-phrase in Unicode!
These two .fetchmailrc entries show the difference between an RPA and non-RPA configuration:
# 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
For example, to download email for the user <philh@vision25.demon.co.uk>, you could use the following .fetchmailrc file:
set postmaster "philh"
poll pop3.demon.co.uk with protocol POP3:
user "philh@vision25" is philh
Received: from punt-1.mail.demon.net by mailstore for fred@xyz.demon.co.uk
id 899963657:10:27896:0; Thu, 09 Jul 98 05:54:17 GMT
To enable multi-drop mode you need to tell fetchmail that 'mailstore' 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)
poll pop3.demon.co.uk proto pop3 aka mailstore no dns:
localdomains xyz.demon.co.uk my-company.co.uk
user xyz is * fetchall
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.
Note that Demon may delete mail on the server which is more than 30 days old; see their POP3 page for details.
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".
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.
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.
fetchall'. A user reports that the 2.2 version
of USA.NET's POP server reports that you must use the
`fetchall' 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.
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 `fetchall' forces it to use
RETR instead.
Also, we're told USA.NET adds a ton of hops to your messages. You may need to raise the MaxHopCount parameter in your sendmail.cf to avoid having fetched mail rejected.
(Note: Other failure modes have been reported on usa.net's servers. They seem to be chronically flaky. We recommend finding another provider.)
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.
We've had a more recent report (December 2001) that the TOP command fails, returning only one line regrardless of its argument, on something identifying itself as "OpenMail POP3 interface".
Workaround is to use "mda" keyword or "-mda" switch:
mda "sed -e '1s/^\t/Received: /' | formail | /usr/bin/procmail -d <user>"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.
Fix: Get an email provider that doesn't suck. The pop-up ads on Geocities are lame, you should boycott them anyway.
This is a customer lock-in tactic; we recommend boycotting MSN as the only appropriate response.
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.
fetchall
flag to ensure that it's recovered on the next cycle.
fetchall option to force use of RETR and work around this
bug.
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 fetchall option.
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.
On Jan 9 2001, the people at InfiniteMail sent me mail informing me that their new 3.61.08 release of InterChange fixes this problem. I don't have any reports one way or the other yet. S15. How can I use fetchmail with GMX?
Use IMAP. The GMX StreamProxy server behaves badly on
authentication failures, sending back a non-conformant error message
(missing an -ERR tag) that confuses fetchmail.
Alan Schmitt has added a similar --with-socks5 option that may work better if you have a recent version of the SOCKS library.
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.
The NRL IPv6+IPsec software distribution can be obtained from: http://web.mit.edu/network/isakmp
The inet6-apps kit can be obtained from http://ftp.ps.pl/pub/linux/IPv6/inet6-apps/.
More information on using IPv6 with Linux can be obtained from:
Use the plugin option. This is dead simple with IMAP: plugin "ssh %h /usr/sbin/imapd"
You may have to use a different absolute pathname, whatever the location of imapd on your mailserver is. 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 imapd, using the more secure ssh authentication (as well as getting ssh's end-to-end encryption). Most IMAP daemons will detect that they've been called from the command line and assume the connection is peauthenticated.
POP3 daemons aren't quite as smart. They won't know they are preauthenticated in this mode, so you'll actually have to ship your password. It will be under ssh encryption, though, so that shouldn't be a problem.
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 athena-dist.mit.edu). If you have these, compiling in GSS support is simple: add a
--with-gssapi=[/path/to/krb5/root]option to configure. For instance, I have all of my Kerberos V libraries installed under /usr/krb5 so I run
configure --with-gssapi=/usr/krb5
Setting up Kerberos V authentication is beyond the scope of this FAQ (you may find Jim Rome's paper How to Kerberize your site 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).
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.
Now you don't have to worry about your password appearing in cleartext in your .fetchmailrc, or across the network.
Note that there is a known bug in the implementation of SSL_peek under OpenSSL versions 0.9.5 and older that fetchmail occasionally tripped over, causing hangs. It is recommended that you install 0.9.6 or later.
Fetchmail binaries built this way support ssl,
sslkey, and sslcert options that control
SSL encryption. You will need to have an SSL-enabled mailserver
to use these options. See the manual page for details and some words
of care on the limited security provided.
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 /dev/urandom, and this message probably means your OS doesn't have that device.
. 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 is not available in this case.
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.
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".
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.
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.
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.
We have one report (from toby@eskimo.com) that you can sometimes solve
such problems by doing an smtp declaration with an IP
address that your routing table maps to something other than the
loopback device (he used ppp0).
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.
It's also possible that your DNS configuration isn't
looking at /etc/hosts at all. If you're using libc5,
look at /etc/resolv.conf; it should say something like
order hosts,bind
so your /etc/hosts file is checked first. If you're
running GNU libc6, check your /etc/nsswitch.conf file. Make
sure it says something like
hosts: files dns
again, in order to make sure /etc/hosts is seen first.
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.
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.
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.
Try sending yourself test mail and retrieving it using the
command-line options `-k -m cat'. This will dump exactly what
fetchmail retrieves to standard output (plus the Received line
fetchmail itself adds to the headers).
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.
flex
installed. The problem appears to be a result of building with an
archaic version of lex.
Workaround: fix the syntax of your .fetchmailrc file.
Fix: build and install the latest version of flex from the Free Software Foundation. An FSF mirror site will help you get it faster.
Workaround: link with GNU malloc rather than the stock C library malloc.
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).
If this happens, you have a specific portability problem with the code in daemon.c that detaches and backgrounds the daemon fetchmail. The isolated Linux case has been chased down to a failure in dup(2) that may reflect a glibc bug.
As a workaround, you can start fetchmail with -N and an ampersand to background it. A Sun user recommends this:
(fetchmail --nodetach <other params> &)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!
/sbin/ifconfig. If it's over 600, change it in your PPP
options file. (/etc/ppp/options on my box). Here are
option values that work:
mtu 552 mru 552
Another circumstance that can trigger this is if you are polling a virtual-mail-server name that is round-robin connected to different actual servers, so you get different IP addresses on different poll cycles. To work around this, change the poll name either to the real name of one of the servers in the ring or to a corresponding IP address.
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.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]
echo 0 > /proc/sys/net/ipv4/tcp_timestamps
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.
mda option. Your MDA is
croaking while being passed a message. Best fix is to remove the
mda option and pass mail to your port 25 SMTP listener.
The symptom: 'fetchmail -v' retrieves mail fine, but appears to hang after sending the MAIL FROM command