Email notifications in Applications Manager may stop functioning in Applications Manager version 9.3.1 or below.
Restarting Applications Manager fixes the issue
Release : 9.2.x, 9.3.0, 9.3.1
bug in Applications Manager that is fixed in Applications Manager 9.3.2.
Workaround:
Restart Applications Manager processes or service (Windows)
Solution:
Upgrade to fixed version Applications Manager 9.3.2
Bugfix information found here and noted below:
SMTP connections not timing out due to bad connection (AM-1481)
A problem has been fixed where SMTP connections (notifications) were not timing out. The connection timeout for notifications has been set to 30 seconds with a read/write timeout of 3 minutes.