We have a server with about 300 domains on it that handles web and mail services using Linux, APACHE, PHP and QMAIL with the PLESK Control Panel. Recently we have found out that one of the domains has a form on it that is being injected and used to send out SPAM. We don't know which on yet and while we are trying to figure that out we have turned off SMTP outbound connections via IPTABLES.
So the question is two fold:
One: Is there a way to make sure or check that all outbound PORT 25 connections are indeed NOT happening. I really want to make sure nothing is leaving the box.
Two: Is there a quick way to determine which domain on our system the spammer is using, or which form was used to inject the email into?
Any help in this matter would be greatly appreciated.