I'm gonna take the plunge and try to manage my own mail server for one of my domains. I need a server that's at least somewhat gentle on a newb and can attach an X-Envelope-To: header (pulled from the RCPT TO: of the session).

I also need some advice (or URLs) on how to configure the various parts to accomplish this...:

When mail is received, examine the RCPT TO: (NOT the "To:" field) of the incoming mail session and check a LONG list* of "virtual addresses". (Not just an alias, but address@fullyqualified.domainname.com) If mail is addressed to an email address not on the list*, return Unknown User immediately.

(* This list needs to be a text file for easy and frequent editing and updating.)

Would a long text file of procmail directives work here? Or does procmail processing occur after the session is complete? (which means the originating server's message/spam attempt didn't get rejected until after it "successfully" sent it. Boo.)

I'm currently using Ubuntu.