AMSI Problem mit Exchnage 2016 CU 21

Hello,

I've also had this problem with Outlook client connectivity slowing down dramatically since installing Exchange 2016 CU21.  I disabled in web.config as you advised, but still had the problem.

I have cases open with Microsoft and Sophos; impossible for me to tell who's issue it is at this point.

I disabled AMSI on the agent with the "override" feature, as advised by Support.  Waited a while for the change to go through, but the Outlook connections remained slow.

Finally, today I decided to disable AMSI on my Exchange Server by policy from Sophos Central.  This time it worked!  Outlook connections are fast again.

Obviously this is a workaround.  I hope engineers at Sophos, Microsoft, or both can determine the root cause and fix it.  This is an important feature that I'd like to have enabled.

I've just received a reply on a Microsoft Exchange Team Blog (Released: July 2021 Exchange Server Security Updates - Microsoft Tech Community) indicating that AMSI may not be compatible with several antivirus solutions at this time.  Still unclear to me if this incompatibility is caused by Sophos or Microsoft.  If Sophos, it doesn't appear that they're the only provider with this issue.

Hello, Norman.

have you already received an answer to your ticket? Since it is every subject it would be good to get answers to help others as well.

Hi Simon,

No response on my Microsoft ticket yet at all.  Sophos has contacted me for more information, which I've provided.  Hopefully we'll learn more soon.

Hello all, we are facing the same issue, waiting now for the reply from sophos.

Hello all, we are facing the same issue, waiting now for the reply from sophos.