How to find a Spam Generatir in my Network

Dear Experts

i am running most of my clients on Windows XP with Syamantec Endpoint Virus Protection & having Exchange 2003 Enterprise Server, from last few days I have constatnly been black listed on various spam engines, shown at MXTOOLBOX, How can I check which of the computer is generating these thousands of spam messages.

I have run a relay check & found that relay is not allowed, I have also blocked the HTTP & HTTPS access to my mail server from outside.

Please Help.
inteqAsked:
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Pieter JordaanConnect With a Mentor Senior Systems Administrator - Web hosting and Network Security.Commented:
Hi

I had a similar problem a while ago, and found a computer on my network that delivers email straight to the mail server port 25. It could manipulate the entire email, including from, to and attachments.

We had to configure exchange connectors for all the authorized mail hosts, and block everything else.

I found the computer by changing the mail server IP address, and then configuring a pfsense firewall to use the IP address so that I could filter through the connections, and forward packets to exchange.

There must be a simpler way to find the machine / machines that are delivering the emails.
I did not look at Windows tools to do that.

The simplest would be to change the exchange connector to only accept emails from specified IP addresses, or to block your LAN IP range on that port.

Depending on the size of your network, you could try a different Anti-Virus, like AVG - http://free.avg.com to try and find it. I haven't had good luck with viruses using Syamantec. I'm sure AVG will pick up virusses that Syamantec missed.

Good luck.
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Pieter JordaanSenior Systems Administrator - Web hosting and Network Security.Commented:
True.

I suppose the 30 day trial will also do the trick.
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phototropicCommented:
Please share points with BitFreeze.  His initial post is the meat and potatos of this answer.
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younghvCommented:
Sorry - thought I selected the "Split" option.
I am going to "Object" to this, so a Moderator can make that happen.

Good call - thanks.
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ModernMattCommented:
Starting the process to split the points.

Thanks, all!

ModernMatt
Experts Exchange Moderator
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