Virtual Domains and qmail

If you have hundreds of users for a virtual domain, you can avoid the hundreds of .qmail-xxx files with a small script that calls qmail's forward command.

Instead of creating individual .qmail-xxx files in the virtual domain master user's home directory, create a single .qmail-default file containing the following line:

|/usr/local/bin/qmail_db_lookup /home/master/qmail_db

with /home/master/qmail_db modified to reflect the home directory of your virtual domain. You can then create (or adapt from your existing /etc/aliases) the file /home/master/qmail_db, consisting of lines with the virtual domain user, a colon and the forwarding address(es). The special user name “-” indicates where mail should be forwarded for any users not explicitly listed. If the “-” user name is not provided, mail for nonexistent users will be bounced. A sample qmail_db file might look like this:

-:  postmaster@somewhere.com
john.smith:   john.smith@alo.com
carl.jones:   cjones@test.net
karen.quincy: kquincy
all:  john.smith@alo.com cjones@test.net kquincy

Listing 1

A more substantial package for supporting /etc/aliases, qmsmac, is available with qmail. qmsmac supports arbitrarily deep-nested aliases and long aliases but, like sendmail, requires you to rebuild a database of aliases every time your /etc/aliases file is changed.

qmail appears to be a speedy and robust replacement for sendmail. We've had qmail running on our Linux Internet server for many months now without a single glitch. The additional features provided by qmail could be useful to those of you hosting several virtual domains from a single Linux box, and the simpler configuration is an added bonus.