Courier uses the gdbm database library to write the userdb file, and
exim uses the db2 database library to read it (if you configure it to
This is very inconvenient as then exim cannot read courier's userdb file
in order to deliver mail. I would suggest that courier be changed to use
the db2 library, but as long as everything that could concievably want
to access userdb uses the same db lib I don't particularly care which
one they use.