[Mimedefang] This mail's for you... NOT!

[Matthew.van.Eerde at hbinc.com]

Shively, Michael @ FRE wrote:
> I find messages in my outgoing queue for sendmail but the messages are
> addresses to other domains.

This could be normal.  Return receipts, undeliverable notifications, etc.
Are you using some kind of address verification on the perimeter server?  By this I mean, do you make sure that the RCPT TO email address exists on the Exchange server (via LDAP, say) at RCPT TO time?

> Luckily I decided to use my Exchange
> Server as the Outgoing mail server and I configured my 3rd party
> firewall to deny the Fedora box access to port 25 outgoing.

Gack!  Bad idea.

> So, I am FaIrLy CeRtAiN that I am not being used as a relay.
> How do I prevent my Fedora box from accepting mail for other domains?

Check to see what the originating IP for these mail items is.  If it's 127.0.0.1 you're OK and this is normal.  Otherwise something's broken.  Find it and fix it.

> (FYI: I receive approx 1500 mail messages per day (90% spam) LOL)
> (FYI: Only a few (1-5) messages are accepted for other domains per
> day) 

> Also,
> Most of the spam messages that I receive are addresses to non-existing
> users... Mailing list I guess...  Can I setup a way to accept mail
> for only a list of e-mail addresses?

Answers my previous question.  Yes, you sure can.  What I do is generate an access database of the form

To:joe at example.com RELAY
To:fred at example.com RELAY
...
To:example.com REJECT

> It seems like a shame that spamassassin and mimedefang have to work
> so hard scanning messages that are not even sent to a real recipient.

Yes, sendmail should be catching these earlier as above.  If not you're just participating in the global joe-jobbing of falsified From: addresses.
 
> Thanks,
> Michael
> New to Linux but learning fast!

You've taken your first step into a larger world...

Matthew.van.Eerde (at) hbinc.com                 805.964.4554 x902
Hispanic Business Inc./HireDiversity.com         Software Engineer
perl -e"map{y/a-z/l-za-k/;print}shift" "Jjhi pcdiwtg Ptga wprztg,"