The mailflow between my Exchange 2010 and 2013 has stopped.

Exchange 2010 gives a 4.4.2: Connection Dropped due to Socket Error.

When I telnet on port 25, I get no more than a blinking cursor. Telnet from local machine works ok.

No firewalls enabled, no virussca

Hi Robert,

Thank you for your question.

Could you give us more details about error information?

Did message flow could pass Exchange 2013 to Exchange 2010?

Did Exchange 2013 send email to Internet?

Did you create send connector between Exchange 2010 and Exchange 2013?

We could create an Internal connector on Exchange 2010 to point to Exchange 2013.

We could refer to the following steps to troubleshoot:

1. Make sure the correct certificate which have deploy on Exchange server and didnt expired;
2. make sure the message flow could be caused by the third party software;
3. Create a new send connector and disable the previous send connector between Exchange 2010 and Exchange 2013 to check if the issue persist;
4. Active the SMTP log to check if there are any error log;

I suggest you send the error information to ibsexc@microsoft.com for our troubleshooting.

If there are any questions regarding this issue, please be free to let me know. 

Best Regard,

Jim

Hi Jim,

after burning the midnight oil, I found out that the WMI Certificate for the IIS service had been damaged. Chose a different certificate, and everything started working again.

Used the opportunity to immediately install CU7.

Thanks for the help.

Kind regards,

Robert