I have read this a few times on these threads but for some reason this seems to be still an issue.
We have been using SM since v7. Gone through all of the versions, however, since SM 12 (I think!) we have had an issue whereby SM will just eat more and more RAM the longer the server is left up. On one server we will see the RAM usage go from 300MB to 800MB within a few days with the exact same usage...the worrying thing is when then the server is not being used (through the night) it might drop to 750MB ish but never drops back to anything lower...until we restart the server for some other maintenance and it will then happily use 350MB for a week....then it will start to creep up again.
I understand that 800MB is not much RAM...the issue is that SM seems to keep the RAM and not release it. That seems to be pretty bad practice and a potential bug/RAM leak?
The overall issue is simply that no matter what usage the Email Server gets SM will just increase it's RAM usage.
Just to note, this is on a 2008 R2 OS. We have a test server running 2012 and I cannot get that to have the same issue....however I will be moving some domains onto it for real world testing shortly so hopefully that will show any issues.