Regarding: "Virtual Users And Domains With Postfix, Courier And MySQL" http://www.howtoforge.com/virtual_postfix_mysql_quota_courier I set this up to use for smtp-auth, and am finding that SBC is (at the least, other ISPs may also be) filtering outgoing connections from its dialup and DSL customers to port 25, so it doesn't work so well. (Ref. http://support.sbcglobal.net/article.php?item=4640 ). Now, they suggest listening on port 587 as per RFC 2476 ( http://www.faqs.org/rfcs/rfc2476.html ), but I've already got customers using it on port 25. Listening on both ports would work great. Will postfix listen on multiple ports or can I run multiple instances of smtpd simultaneously? What do I need to update in the config for this? Thanks.