Recently upgraded to June 2017 and emails are no longer being sent.
I see the following error in the log
Failed to send e-mail for bucket f9593189-dfce-4fa3-8cdc-780e09224eaa. Failure sending mail.
Not very descriptive. Any ideas?
Found it, apparently my smtp server no longer accepts TLS connections.
Once I unchecked that box emails were sent.
Retrieving data ...