I'm doing a hybrid install of The Perfect Setup - Debian Sarge (3.1) and Virtual Users And Domains With Postfix, Courier And MySQL (+ SMTP-AUTH, Quota, SpamAssassin, ClamAV) to replace my Qmail rocks server On the perfect setup I've skipped the Quota, DNS server, Postfix/pop3/Imap, Courier-Imap/Courier-pop3, proftpd and webalizer, using Virtual Users And Domains With Postfix, Courier And MySQL (+ SMTP-AUTH, Quota, SpamAssassin, ClamAV) in their place. I have DNS and DHCP running on the Qmail rocks server. I have not yet installed the quota patched version of postfix. DNS, ProFTPd, webmail and webalizer (and possibly ISPconfig) are planned for later. Everything appears to be working well. I'm looking for a good web management interface for setting up email users and websites. Does anybody have any recomendations for this?
ISPConfig - developped by Falko and Timme who run this site - integrates perfectly with the perfect setup for debian... But I don't know if it'll work with your setup...
But ISPConfig is not compatible with the virtual users used by your Postfix setup... It uses system users.