I would be curious to know if the problem persists on a fresh install vs upgrade / downgrade. Are you able to do an export of all the data, then completely un-install and re-install 9229 (or 9168 which ever you prefer)? There have been a few memory leak issues reported by various people on various platforms and builds, so i'm more curious if something in the update process changes the actual accounts causing the memory leak vs SM introducing a memory leak?

We are currently running on 9182 on a dedicated windows 2019 server and haven't noticed any issues. We are holding off on the upgrade because of this specific issue.

Sorry, my mistake... the previous version was 9182 for me too (I've just edited the post to correct). I had no problem with this version either.

@Richard Laliberte : unfortunately I can't do this easily... This is an on-premise production server in a customer's data center.

Since I can't create a new server in the customer's data center, I would have to copy all the data to MY data center and set up a test server there.

But then I would be missing 62 users who can simulate the customer's mail usage...

a bummer. That will make it a bit more difficult to track down the actual cause of the leak. Guess we will hold off as well upgrading so we don't run into similar issues... although i thought i read somewhere that someone got a 9230 build and it was working well.

Curious though, 1) is the install itself a long running upgrade, or did you do fresh installs at some point along the line. and 2) are the user accounts also older, maybe going back several years worth of updates? (programmer in me coming out now trying to help SM get all the data they can lol) We are looking at upgrading our windows box at some point from 2019 to 2022 (possible 2025) and i've been on the fence about asking for a fresh install and running an import wizard on SM just in case there is left over junk code (we've all seen it with anything Microsoft related lol) 

In the meantime it seems to have calmed down a bit and now it doesn't happen so often... Who knows!

To be safe, I set up a PowerShell script that checks the RAM used by the "MailService" process, restarting it if it exceeds a certain number of Megabytes...

I run it at regular intervals every 10 minutes, so that if the RAM used exceeds a certain level it restarts, otherwise not (this way I avoid unnecessary restarts...)

It works wonders!