NDR attack

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.
jmv973Asked:
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Alan HardistyConnect With a Mentor Co-OwnerCommented:
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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jmv973Author Commented:
2003
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jmv973Author Commented:
I have verified that it is enabled but still no luck?
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Alan HardistyCo-OwnerCommented:
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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