After setting up name-based virtual web hosting for Apache, I’ve just set up virtual mail hosting for my new company, Printscreen GmbH, using postfix – and it was amazingly simple! :) For some basic virtual mail hosting using normal UNIX/Linux user accounts, all you need is a plain-text file (‘/etc/postfix/virtual’) that maps virtual mail addresses to the actual user accounts and two additional lines in main.cf:
/etc/postfix/virtual:
postmaster@example.com postmaster
# Uncomment entry below to implement a catch-all address
# @example.com jim/etc/postfix/main.cf:
virtual_alias_domains = example.com
virtual_alias_maps = hash:/etc/postfix/virtual
Then just execute
# postmap /etc/postfix/virtual && /etc/init.d/postfix reload
Voilà!
The nice postfix readme file for this and some more complicated virtual mail hosting configurations:
http://www.postfix.org/VIRTUAL_README.html
Another, possibly helpful howto (search):
http://www.freebsddiary.org/postfix.php
For setups using a MySQL database as a backend for storing the mappings, see Google. I currently don’t need this and hence don’t like to introduce any unnecessary MySQL dependency to my postfix server – remember the KISS principle ;)