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NDR attack

Posted on 2011-03-17
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Last Modified: 2012-05-11
I have recently applied some known fixes to resolve an NDR attack but am unable to receive mail now but am able to send, would anyone have an idea of where I should be looking?  thank you in advance.
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Question by:jmv973
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Alan Hardisty earned 2000 total points
ID: 35162100
You have probably taken off the Anonymous Authentication from your Receive Connector / SMTP Virtual Server - that will kill your mail-flow dead in it's tracks.

What version of Exchange do you have?
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by:jmv973
ID: 35162106
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by:jmv973
ID: 35162118
I have verified that it is enabled but still no luck?
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by:Alan Hardisty
ID: 35162136
Okay - if the Anonymous Authentication is enabled on your SMTP Virtual Server, then is port 25 open inbound on your firewall?

Check on http://www.canyouseme.org and test port 25.  You should see SUCCESS if all is well.

If that doesn't work - what did you change exactly, or what did you follow to eliminate the NDR attack?
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