Notifications (Event) stopped working today at 3pm

[Gnorizo]

Help... I'm stumped. We have a rule under the "Notifications (Event)" setting that sends an e-mail to the customer whenever a ticket is closed. But for some reason, that rule suddenly stopped working today around 3pm. Now, messages are no longer sent out when a ticket is closed, but the message isn't even appended to the ticket as an article. (Even if the e-mail gets stuck, I'd still expect it to show up in the ticket's article list.)

We didn't change that notification rule today. OTRS confirms that it hasn't been changed since 7/6/2012.

All other outgoing e-mail messages are working from OTRS, including reply auto-responses (for new e-mail), agent initiated replies from the ticket details UI, etc. The only outgoing messages that aren't working are from the "Notifications (Event)" rule. We even switched our Core::Sendmail SendmailModule setting from "Sendmail" to "SMTP" and pointed it at our Exchange Server, just in case that might help. But it didn't affect anything - all outgoing e-mail messages still worked except from the "Notifications (Event)" rule.

OTRS is behaving as if the event notification rule isn't even running.

Even more strange, event notification not only broke on our internal OTRS server, but it ALSO broke on our paid OTRS-On-Demand server! Both servers around the same time, without us making changes to the event notification configurations. That seems like too much of a coincidence.

Has anyone else encountered this issue? And either way, what do you suggest as a next step in diagnosing this issue? I'd like to confirm if the event notification rule is even running in the first place. Is the event notification code run from a periodic cron job/scheduler, or does it run real-time whenever a ticket is closed? Please help! Thank you.

-- Chris

PS: We're running OTRS version 3.1.7 on CentOS 6.2, and our OTRS-On-Demand service is also running OTRS version 3.1.7.

[crythias]

Does OTRS System Log indicate a problem?
My guess is that the notification Sender email address is being blocked because it isn't configured. Either that or you changed something that the Event reacts to.