I've a Debian sarge testing server (i'd tried with stable too) and a month ago i'd to reinstall, but the server never was the same
in the past I was running with courier+postfix+mysql but at reinstallation i've the same error every time i try to connect via smtp (courier pop & imap are ok):
Nov <timestamp> lared postfix/trivial-rewrite: fatal: mysql:/etc/postfix/virtual.cf(0,100): table lookup problem
i've tried using mysql 4.1 and 5.0 (i don't remember what version of mysql-server was running before), it's all ok, all users, all passwords... i tried with root user too!!