Blacklisted : CBL - Exchange 2010 - Need Assitance

Have Exchange 2010 has been running fine, no issues.
Got call from client, cannot send.
Checked MX Toolbox
Listed on SORBS, Spamhaus Zen, CBL
CBL says trojan or botnet is on network

Checked server, Queues are not filling up with outbound mail, thus I don't think I have a compromised user account and not relaying, that I can tell.

I am in charge of the server side of the house, what are the steps I should take to verify the server is not compromised.

Please advise
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tech911Asked:
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Alan HardistyConnect With a Mentor Co-OwnerCommented:
Make sure you block TCP Port 25 outbound for all IP addresses other than the Exchange server if you haven't already.

If you have already, then you have a problem on the server, if not, then it's more likely a network computer.

Alan
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Tony GiangrecoCommented:
Run a full anti virus & anti spyware scan on all systems.  I'd run a few different apps to verify everything is clean.

Start with http://windows.microsoft.com/en-us/windows/security-essentials-download on all Pc's

Follow up with Malwarebytes and check all boxes for popups and browser hijacks.

Some spyware and virus apps have their own SMTP engines that bypass Exchange to send mail.
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tech911Author Commented:
Ran Sec Essentials and MWbytes on Server, Clean.
Desktop Team is checking User Desktops
Anything else I should be doing or looking at on the server?
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Tony GiangrecoConnect With a Mentor Commented:
If you have a firewall, see if it tells you what box is sending out Smtp traffic. You can also setup anti spam service for incoming and outgoing mail. We have used this service on all our clients and it works very well.

This service quarentines incoming and outgoing spam which should stop you from being black listed again. It should also trap the outgoing spam you have right now.

Take a look at GFI max Mail Essentials
www.gfi.com
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