Exchange 2007 application log error Event ID 1035

I am seing the following error every 4 to 5 min appearing in the exchange 2007 application logs:
Event ID 1035
Inbound authentication failed with error LogonDenied for Receive connector Default 'Servername'. The authentication mechanism is Gssapi. The source IP address of the client who tried to authenticate to Microsoft Exchange is [

This is not an internal address... has anyone seen this before?
Should I be conserned about it?
Does anyone know the fix?

Thanks Much
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mass2612Connect With a Mentor Commented:

Do you have your mail being directly relayed from the Internet to your Hub transport server that is generating these errors?

Sounds like an authentication issue with your default recieve connector. You may want to check out this thread -
I dont see any solution posted there.  Can you give us more information on how to resolve this.  I am seeing the same error as above too.
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