Business partner recieving 4.4.7 errors when sending or replying

[mlchris2]

I have a business partner based in Costa Rica and over the past month or so I have been having problems receiving emails (whether generated or a reply) to any user in my domain.

The partner receives a "4.4.7 Delayed" warning message and then a few days later they will receive a " 4.4.7 Could not deliver the message in the specified time limit. Please try again or contact your system administrator" error message.

They receive all of our email communication just fine. I

If they send emails to a yahoo or hotmail address that we have setup, the messages send/receive/reply just fine.

So I checked all my systems;

*MXlogic spam filter and logs. I whitelisted the partner domain.
*IPS (Nitro 1225). I whitelisted the partner domain as well.
*Exchange 2010 logs and show no trace of any email messages from partner, just what was sent.

So I did some research on the web and found this to be a DNS record. I did a DNS lookup and they have PTR records setup, which is what I thought the problem initially could have been.

I am having no trouble receiving emails from any other person located in any other part of the country... just this partner.

I am awaiting a response from their IT dept to help diagnose as I feel it's not any of my systems causing the problem.

Can someone offer any insights that I could check into to resolve this issue?



Mark C.

 

[noveyron]

Tell them to get a reverse DNS entry for their domain pehaps?

 

[mlchris2]

Since you mentioned, I checked mxtoolbox website and found two things that might cause issues;

* SMTP test for ip shows a warning; " Warning - Reverse DNS does not match SMTP Banner".

* Also ip shows on a RBL at UCEPROTECTL2







Mark C.

 

[TechyMcSe2k]

Highly valuable as well:

https://www.testexchangeconnectivity.com/

http://www.samtechconsulting.com

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