add Maildir support

add MH support

start using private variables?

finish man page

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

perserve atime of 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 ?