Outgoing mail disabled unexpectedly

Occasionally we run into customers complaining that they do not receive notifications from their instance anymore. In several cases we have found out that the outgoing mail server was disabled. We have not been able to find out WHY it had been disabled.

If you disable the outgoing mail manually, you will see the following line pop up in the access_log.

/secure/admin/DisableOutgoingMail.jspa?atl_token=BA5K-BTOS-Z92L-H4OB|28b6e2eeb6ead0147d2e1e5d6ef7045af80974fa|lin HTTP/1.0" 302 20 7511 "https://xxxxx-xxxxxx.atlassian.net/secure/admin/OutgoingMailServers.jspa" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.17 (KHTML, like Gecko) Chrome/24.0.1312.69 Safari/537.17"

I have investigated further and have not been able to find any other log entries which might indicate the mail server has been turned off. Perhaps it doesn't start up after a deployment or something, though I have not been able to find data that supports this.