Mail fetch process keeps getting stuck...

[quantumschema]

Hey all!

So I've been having a problem for a while now I can't seem to put my finger on what's causing it. The mailfetch process or OTRS agent will just suddenly become hung not processing any new incoming emails. The current config is roughly the following:

OTRS version: 5.0.19-02
OS: CentOS 7.3.1611
Hardware: 2 vCPUs 4GBs RAM (Virtualized in AWS [t2.medium])
Mail Protocol: IMAPS
Mail provider: Office 365 (Exchange Online)
Number of mailboxes: 8
Mail fetch schedule: Every two minutes ( was 1 minute but I increased it to 2 minutes a while back to see if it resolved the issue)

There seems to be no pattern to it all. It was working this morning but then just happened to stop mid-day. The only way I've seen to immediately resolve the issue is to:

1. Stop the OTRS Agent ( sudo -u otrs /opt/otrs/bin/otrs.Daemon.pl stop )
2. In MySQL run:
2a. truncate otrs.scheduler_task;
2b. truncate otrs.process_id;
3. In CentOS:
3a. ps -u otrs
3b. Kill all running processes ( sudo kill -9 [process#] )
4. Start the OTRS Agent ( sudo -u otrs /opt/otrs/bin/otrs.Daemon.pl start )

Once the agent starts again, it immediately starts fetching mail and will proceed to do so for the next several days (1-10 days) where it randomly stops again.

I've look in almost every log file I can find and think of but nothing shows an error related to mailfetch so I'm at a complete loss.

Anyone have any thoughts?

[quantumschema]

Okay.... I went ahead and upgraded to OTRS 5.022-01 and I'm monitoring to see if it continues. I noticed after the upgrade when I ran "otrs.CheckModules.pl" that "Mail::IMAPClient" was noted as being Not Installed. I don't recall that missing before but I went ahead and installed "perl(Mail::IMAPClient)" as recommended so I'll see if that makes any difference.

Any input would still be greatly appreciated.