SQL Server 2016 SP2 CU1 deletes Database Mail file
Installing the above mentioned CU deletes this file...
C:\Program Files\Microsoft SQL Server<instance>\MSSQL\Binn\DatabaseMail.exe.config
It results in Database Mail being queued but never sent.
This appears to be a return to an issue caused by SP1 CU1, as described here...
To fix, follow the workarounds in the article. Hopefully this latest CU hasn't broken anything else!
CU4 explicitly mentions this issue (https://support.microsoft.com/en-gb/help/4476949) and has a fix - and yes, it does fix it.
Just applied CU3 to SQL2016 SP2 - same issue. I think this is going to keep happening for every CU/SP from now.
Danielle Paquette-Harvey commented
I though this problem was only with SP1 but it's there in SP2 CU2 and in SP2 GDR. I had to install .Net 3.5 on new servers also. Very annoying bug.
Jones, Samuel commented
verified here - we updated from SP1 CU8 to SP2 then SP2 CU2 and it broke database mail in our AlwaysOn Availability Group. Interestingly enough, it did not break on a separate server with the same update. That machine was running on the default service account for SQL Agent and was not in an AG - maybe that narrows it down.
I too have had this issue after applying SP2 CU2.
I had previously fixed the issue by manually creating the config file - will await CU3 to see if it happens again
This appears to be the same if you apply CU2 to 2016 SP2