Here is the free command on my server:

[root@nss ~]# free -m
total used free shared buff/cache available
Mem: 1997 1598 37 7 361 335
Swap: 511 48 463

Yes, I am getting occasional invoked-oom messages in my messages log for mysql that correspond to the failures. It looks like mysql gets restarted but I suspect that one or more zarafa servers isn't. I will check the next time this happens.

I have used Zarafa successfully in several large organizations (with more capable local servers) and have been happy with it. Particularly because it supports activesync for Outlook 2013 and 2016. Not my email client of choice but my wife depends on it for tax and quickbooks work.

I do have the apache web server installed but, I believe, zarafa uses a sandboxed copy, not the general use marketplace install. I can remove that server and will try to see what other marketplace products I can uninstall. The zarafa server was getting heavy use as I moved thousands of emails in multiple folders from local storage to zarafa. That activity might have caused the failure.

I would still like to find out how to stop the zarafa servers mentioned in the original post from starting on reboot. Another option might be to find a way to test if specific servers are running and either start or stop them using a cron job. Will take some research.