I'm experiencing the same problem.

Last not a auto update took place. There are 2 strange things in my log about the update:

016-10-05 00:06:22,878 WARN  users.f - Config file config/UserConfig.xml not found. Cannot continue reading.
2016-10-05 00:06:22,878 INFO  users.f - UserConfig.xml will be extracted from /share/MD0_DATA/.qpkg/Xeams/config/archives/CONFIG_20161003.zip
2016-10-05 00:06:23,488 WARN  users.f - Config file config/UserConfig.xml not found. Cannot continue reading.

And after the update no mail is received on the internal mail server. The log is stating it can't connect:

2016-10-05 00:06:44,494 WARN  smtp.b - Unable to start TLS connection to 192.168.2.2, recipient: user@dom.com, sender: user@dom.com - Error: Remote host closed connection during handshake

I do not have TLS/SSL enabled (never had) and can't see anything in the config regarding something with SSL enabled.