Yes...I've seen this article which pointed me to exclusions for Exchange 2016. However, we upgraded SEP and NOT Exchange so you'd think the exclusions we used in SEP 11 would still be applicable in SEP 12.
Anyway, due to this issue, our Exchange admin had to migrate users to our 2nd server (in a DAGS) which is still running SEP 11 because if not, we couldn't view our Sent messages. I even had an issue myself in my Outlook 2013 whereby a message I had replied to didn't remove the DRAFT tag until I was redirected to our 2nd mail server.