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How do I tell which users are depositing spam in the exchange outbound queues?

Posted on 2011-03-01
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Last Modified: 2012-05-11
Queues getting filled up with spam. Someone obviously has a virus. How do I tell how they got here?
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Question by:leesobo
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Expert Comment

by:Alan Hardisty
ID: 35013157
Please have a read of my article to see if you have an NDR issue or an authenticated relay issue:

http://www.experts-exchange.com/Software/Server_Software/Email_Servers/A_2427-Problems-sending-mail-to-one-or-more-external-domains.html
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by:leesobo
ID: 35013341
I've checked. This is not an open relay. I do believe it's coming from inside. Endpoint protection is showing all clients good.
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Expert Comment

by:Alan Hardisty
ID: 35013363
I'm not talking about an open relay - I'm talking about an authenticated relay.

Looking at the queues on your server - who are the senders of the emails?
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Expert Comment

by:Alan Hardisty
ID: 35013370
Wireshark should be able to tell you if the spam is coming from a local computer on the network:

http://www.wireshark.org/
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Author Comment

by:leesobo
ID: 35013390
I've installed wireshark and have scanned. For some reason, I"m only getting packets from 1 pc sending to the server. What should I be looking at between the workstation and the Exchange server. Tried port 25. That didn't work.

The address is pcsolutions@television.com. No such address exists internally.
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Expert Comment

by:Alan Hardisty
ID: 35013408
So the sender is pcsolutions@television.com?  If that is the case - please read my article again and ramp up the logging.
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Expert Comment

by:Alan Hardisty
ID: 35013430
A quick way to be sure the problem isn't external (authenticated relay) is to remove Basic & Integrated Windows Authentication from your SMTP Virtual Server and restart the SMTP Service as per my blog article:

http://alanhardisty.wordpress.com/2010/12/01/increase-in-hacker-attempts-on-windows-exchange-servers-one-way-to-slow-them-down/

hat should only allow anonymous users (mail servers) to send you mail but will cut off spammers / your external users if you have any sending your server mail via SMTP / POP3.  If you don't have any users sending you mail this way then removing those authentication methods won't cause you any issues.
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Author Comment

by:leesobo
ID: 35013491
I read your article and did as suggested. How does this impact internal users trying to send mail via outlook?
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Alan Hardisty earned 500 total points
ID: 35013631
Internal users won't be affected.  Only External users trying to send via SMTP direct to your server (if you have any such users) will be affected, plus of you have an authenticated relay, it will stop it dead in it's tracks.

If you have lots of queues on your server, you can download aqadmcli.exe to empty the queues very quickly:

ftp://ftp.microsoft.com/pss/Tools/Exchange%20Support%20Tools/Aqadmcli/aqadmcli.exe

For usage instructions - please visit this link:

http://community.spiceworks.com/how_to/show/267
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