Hello Douglas,
I'm not complaining about this issue, just explaining what is going on and what we are doing to avoid issues when upgrading, for exemple to avoid the installer telling you you need to reboot.
Since a few years when I'm doing the upgrade or even a simple restart of the service, I always do it like this:
1) Stop the service from the service manager
2) Monitor the mailservice.exe process in process explorer or task scheduler and wait until the process is really gone
2) Do the upgrade (or start the service again) depending I'm doing a restart or upgrade.
In previous versions (a way back), nothing prevented mailservice.exe to run multiple times, so for example doing a restart would result in double mailservice.exe running, bringing issues like ports binding errors or worse, both process writing to the same files and creating corruption.
This is not happening anymore, hopefully, and is a great step ahead.
Still, an addition to the installer could be that after it requests a service stop and after it receives the feedback from the service manager, it could then monitor the running processes and check for mailservice.exe presence, and wait for it to really disappear before going on with the upgrade.
Well that would be how I would do it, if I was in charge of the installer script.
But with current status, on "big" rigs, and as long as you make sure the service has properly stopped before doing any upgrade or start of the service, there a no problems.
Kind regards