Some background on our mail setup:

Incoming mail hits my spam removal service (spamstopshere) it is forwarded
to my smtp relay that is in our dmz then its forwarded through to our exchange 2003 server(SBS).

Outgoing mail travels to the exchange server where it is forwarded to the smtp relay in our
dmz and on to the remote host.

I'm no exchange admin but this setup seems to be working fine.

**** The problem is that i get dozens of errors messages every day in the system event log on the SMTP relay (win2003 web ed. running IIS smtp relay). Each message is to a different host and they all are mail
to destinations that my users have not sent mail to (almost all in south america).  It looks like my relay is being used by spammers.

System Log Errors:
System log smtpsvc event id:4006
Message delivery to the host '64.74.96.243' failed
while delivering to the remote domain 'motmail.com'
for the following reason: The semaphore timeout
period has expired.

System log smtpsvc event id:4006
Message delivery to the host '89.38.58.7' failed while
delivering to the remote domain 'slidelim.com' for the
following reason: The remote server did not respond to
a connection attempt.

Can someone tell me whats going on and If I should be alarmed.
Please Advise.
Thanks,
Phil...