[Sorry for this OT, but that’s a severe worldwide bug]
A major bug has hit the Microsoft Exchanges on premise since January 1st 2022, because of using a int32 variable that long exceeds the maximum value of 2,147,483,647 causing the service goes error and blocking the queue mail.
A first solution released by the community was to disable the malware filtering service with the following powershell lines:
Set-MalwareFilteringServer -Identity <nameserver> -BypassFiltering $true
Restart-Service MSExchangeTransport
Microsoft yesterday released a powershell .ps1 that tricks the service by “unlocking the month of December 2021 to infinite days”, so today would be 34 December 2021.
Honestly, I don’t know if this can be considered a good solution.
For more updates, there’s a dedicated subreddit:
https://www.reddit.com/r/sysadmin/comments/rt91z6/exchange_2019_antimalware_bad_update/