Re: Fining source of email messages relaying through Exchange Server

Where are you seeing the messages being returned as undeliverable?
--
Ed Crowley MVP
"There are seldom good technological solutions to behavioral problems."
..

"NG" <NG@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message news:F4B3FD1F-B1A2-49B6-8404-8B100FF4502E@xxxxxxxxxxxxxxxx
A few days ago I was notified by my ISP that a large amount of spam was being
sent from my mail server. They have blocked port 25 until I can resolve the
issue. I stopped forwarding port 25 traffice to my mail server and I checked
the box to require authentication for mail relay.

After taking these steps, I am still seeing a handful of emails being
returned as undeliverable (because the port is blocked preventing them from
being sent). These emails are addressed to random email addresses and have
spam subject lines. I am trying to figure out where these emails are coming
from. I have shut down all client computers on the network with the
exception of two that are required. I have run a virus scan on all client
computers using Kaspersky and on the SBS 2003 server using AVG SBS. Nothing
was found.

I am trying to figure out if the mail is coming from something on one of the
clients since I have blocked port 25, or is there another way for email
traffic to be relayed through my server besides port 25? The mail that is
being sent is not appearing in an outbox, but does show up in the queue on
the Exchange server.

Any help would be greatly appreciated so that I can turn my mail server back
on. Just as a side note, I am planning to upgrade to SBS 2008 in the coming
weeks, but I wanted to wait until this issue was resolved.

Thanks,
Nick

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