We've confirmed that all systems are back to normal with no customer impact as of 03/25/2019 21:15 UTC. Our logs show the incident started on 03/27/2019 09:15 UTC and that during the 36 hours that it took to resolve the issue some customers may have received malformed failure anomalies alert mails. The metric and availability alert emails were not impacted.
Root Cause: The failure was due to a recent change in our mailing service.
Incident Timeline: 36 Hours - 03/25/2019 21:15 UTC through 03/27/2019 09:15 UTC
We understand that customers rely on Application Insights as a critical service and apologize for any impact this incident caused.
Initial Update: Wednesday, 27 March 2019 09:02 UTC
We are aware of issues within Application Insights and are actively investigating. Some customers may have received malformed failure anomalies alert mails. The links in the alert mails still work correctly. The metric and availability alert emails were not impacted.
Work Around: As a workaround, Customers who received the malformed emails can directly verify the details on the Azure Portal.
Next Update: Before 03/27 11:30 UTC
We are working hard to resolve this issue and apologize for any inconvenience. -Varun