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Exchange server used as spam relay - how to stop?

Posted on 2010-11-19
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Last Modified: 2012-05-10
Our customer has got complains from the broadband company that spam is sent from their IP-number.

They have a Exchange server 2003.

In the "message tracking center" in System manager, I am unable to see theese exemples of sent spam. But I can see all the normal traffic in/out from the exchange server.

What else can I do to track theese spam sent from their IP-number? And what can I do to lookup the server from outside users beeing able to relay throw this machine?
> * Date: Wed, 17 Nov 2010 15:36:34 -0700

> * From: Order Pfizer Online <ifecyei4430@telia.com>

> * Subject: Hi moron, Mega discounts. They Agreement to

> * Host: XXX-XXX-XXX-XXX.customer.telia.com [XXX.XXX.XXX.XXX]

> * Reason: MULTI-BLACKLIST - [S=6 - cbl.abuseat.org bl.spamcop.net] - OurBl DynamicIP BlList - X=pascal H=XXX-XXX-XXX-XXX.customer.telia.com [XXX.XXX.XXX.XXX] HELO=[telia.com] F=[ifecyei4430@telia.com] T=[moron@politicalstrikes.com] S=[Hi moron, Mega discoun

> 

> For more information about these abuse reports: http://wiki.junkemailfilter.com/index.php/Spam_abuse

> To test or be removed from our blacklist: http://ipadmin.junkemailfilter.com/remove.php?ip=XXX.XXX.XXX.XXX

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Question by:Martin_Radbo
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by:Alan Hardisty
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by:Martin_Radbo
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Nice article.

I tried to enable auth. logging= Full, but still nothing appears in the Application log (event viewer). I tried to log in as a normal user, sent an outbound email. I thought I would see this in the log, but I did not.

Maybe I miss something here.
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by:Alan Hardisty
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Thanks : )

Okay - maybe it won't be there to see!

Who are the senders of the emails?  Administrator or random users?
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by:Martin_Radbo
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Random users!
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Expert Comment

by:Alan Hardisty
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Okay - then you have an Authenticated Relay.

Stop and restart the SMTP Service - that should force the spammer to re-authenticate and should hopefully pop up in the App Event Log.
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by:Martin_Radbo
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I thought the thing was to stop all attempts from outside to relay. The normal users do not user this server for smtp relay at all, they always use outlook/exchange or OWA.

I tried restarting SMTP service. Still no entries in log if a normal user sends emails. If there have been any spammers trying right now I have no idea about.
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by:Alan Hardisty
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The alternative if there are no events in the event logs is that either the server has a virus or a client on your network does.

Do you have any Anti-Spam software installed on the server?
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by:Martin_Radbo
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But one of my users in the LAN sends an email and still I can not see anything in the appl. log. Is that normal?  

I do not think we have any virus causing this, I am quite sure it is "outside spammers" using the server as a smtp relay.
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LVL 76

Expert Comment

by:Alan Hardisty
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Okay - check your SMTP Connections on the Server:

Exchange System Manager> Servers> Protocols> SMTP> Default SMTP Virtual Server> Current Sessions
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by:Alan Hardisty
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Also - worth installing a trial of Vamsoft ORF if you don't have any Anti-Spam software on it - I have used it numerous to trace the account and resolve Open Relays.

www.vamsoft.com
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by:Martin_Radbo
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OK. There are no current sessions, maybe I missed to tell you before. But there are spammers using this server since there have been reports about it the last days.

So I need to close the ability to user that server as a relay, there are no need for that what so ever.
Anyone?
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Alan Hardisty earned 500 total points
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Okay - on the Default SMTP Virtual Server Properties> Access Tab> Relay Button - Make sure Only The List Below is Selected and empty apart from the Server IP address and that "Allow all computers which successfully authenticate to relay, regardless of the list above" is not ticked.

Then click on the Users button and make sure that is empty too apart from Authenticated Users and that Relay is not ticked.

Click OK and then restart the SMTP Service.
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by:Martin_Radbo
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Done!

I will wait and see a few days if anything more happen, before I close this question.

Thanks for your help so far.
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Expert Comment

by:Alan Hardisty
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No probs - only close a question down when you have a solution that works for you.

Fingers crossed for the weekend.  If it continues - I am usually around so just post another comment.

Have a good weekend.

Alan
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Author Comment

by:Martin_Radbo
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It is hard to really know if something nasty is going on, but so far we have not received any spam-reports from anyone so I think it works now. WIll check again in a few days.
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Expert Comment

by:Alan Hardisty
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Good news - don't forget to check on www.mxtoolbox.com/blacklists.aspx to see if you are listed and if you are - if the last reported date is recent or when you made the changes to stop the relay.

If it was when you changed the settings - then you have stemmed the flood and should be able to request de-listing.
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