Exchange Server Mail Stuck on Queue due to Microsoft Bug 01/01/2022

SABBIRRUBAYAT - just a note that it's not a cyber attack, it's an int32 conversion issue with the date code of the 2022 signatures that Microsoft still hasn't fixed.

I had also originally disabled malware scanning using the disable scripts last night to get things working, but the problem with this is that the malware definitions/engines are never updated for the FIP-FS service when you do that...it's better to set all your servers to bypass scanning instead.  I had tried this last night before the internet blew up (this is for 2013 but same thing for 2016/2019 - https://docs.microsoft.com/en-us/exchange/disable-or-bypass-anti-malware-scanning-exchange-2013-help).  The problem with that article is it doesn't say to restart the transport service after running the bypass command - but you have to do that for it to take effect. 

If you do it this way, mailflow will work and your definitions will continue to be updated so that hopefully when Microsoft fixes this your servers will be updated so that when you remove the bypass things continue to work (rather than re-enabling scanning, then waiting for the engines to update which takes a long time/breaks your mail flow again).