Hi, @Alexander Petrovski
Thank you for posting your question in the Microsoft Q&A forum.
According to your description, you encountered the problem that the mail flow rule does not work after the Windows update. In order to better find the cause of the problem, I would like to confirm with you whether the Windows update you mentioned is the latest Exchange Server security update or the Windows operating system update?
- If it is a security update for Exchange Server, the problem of the mail flow rule stopping has occurred in a previous security update. You can try the previous solution to see if it can be solved:
- Use the command to check whether all Exchange services are enabled and running.
Get-Service | Where {$_.DisplayName -like "*Exchange*"} | Where {$_.DisplayName -notlike "*Hyper-V*"} | Format-Table DisplayName, Name, Status
- Confirm that the server is not in maintenance mode.
- Confirm that there is enough free space in the Exchange mail queue database.
- If it is an update of the Windows operating system, you can check yesterday's update log to see if there are any changes or errors related to Exchange Server.
Refer to: https://learn.microsoft.com/en-us/exchange/troubleshoot/client-connectivity/exchange-security-update-issues#mail-flow-has-stopped
If you have any questions, please feel free to contact me. If the answer is helpful, please click "Accept Answer" because it can help other members of the Microsoft Q&A community who have encountered similar problems and are looking for solutions. Thank you.
Best,
Jeanne