test exclusive locking works with another test process

add MH mailbox support

finish man page

add option to archive depending on mailbox size threshold 
    + is this a good idea?
add option to archive depending on number of messages
    + is this a good idea?

perserve atime of original mailbox properly

lock any original .gz files (?)

check for symlink attacks for tempfiles (although we don't use /var/tmp)

test for write permission before doing anything

test for missing compression programs 
    + is this a waste of time?

add option - do not compress (?)

Add Makefile with "make install" target ?