Microsoft outage: delays delivering to Outlook, Hotmail and Office 365

Delivery to Microsoft (Outlook.com, Hotmail, Microsoft 365) is recovering

Microsoft is still recovering from its service incident (Microsoft reference EX1550543). The problem was on Microsoft's side. Our platform has run normally throughout, and delivery to other mailbox providers was not affected.

Since about 11:30 UTC (5:30 AM US Central), delivery to Microsoft recipients has improved a lot. Delivery volume is back in its normal range. We're also working through the backlog of mail that was queued during the outage, and those retries make up a large share of what Microsoft is accepting right now. About 3 in 10 delivery attempts to Microsoft are still being deferred, compared with more than 9 in 10 at the worst point. That's still above normal, so some messages to Microsoft recipients may take longer than usual to arrive while Microsoft finishes recovering.

Microsoft reports that recovery is moving forward across Europe, Asia Pacific and North America, and that some users may still see intermittent issues.

What this means for you: You don't need to do anything. We'll keep retrying any deferred mail automatically. If you set short expiration windows on your messages, some messages to Microsoft recipients may have expired before Microsoft accepted them.

We'll keep watching delivery to Microsoft closely and will post again once it's fully back to normal.

Delivery to Microsoft (Outlook.com, Hotmail and Office 365) has recovered

Delivery to Microsoft mailboxes is back to normal. Starting around 17:30 UTC on 12 November, an incident on Microsoft's side (Microsoft incident EX1550543) caused delivery delays. The errors from that incident have now returned to normal levels, and new mail to Microsoft is being accepted at normal rates and speed.

We are finishing the automatic retry of mail that was delayed during the incident. Most of it has already been delivered, and the rest is draining steadily. Some older delayed messages may still arrive over the next while. You don't need to do anything, and you don't need to resend.

If your messages use a short expiration (TTL) setting, some may have expired before Microsoft accepted them. Those messages were returned as bounces and appear in your bounce events.

This incident is resolved, and delivery to Microsoft mailboxes is back to normal.

From about 17:30 UTC on 12 November, Microsoft's mail service returned temporary errors for most delivery attempts. The cause was an incident on Microsoft's side (Microsoft incident EX1550543), and delivery to other mailbox providers was not affected. Microsoft's errors dropped sharply from about 13:30 UTC on 13 November. Delivery was back to normal rates by 14:35 UTC, and Microsoft's error levels have been normal since about 15:10 UTC (09:10 CST).

We queued all affected mail and retried it automatically. Most of it has now been delivered, and the rest of the retry queue will finish over the next few hours. You don't need to do anything, and you don't need to resend.

If your messages use a short expiration (TTL) setting, some may have expired before Microsoft accepted them. Those messages were returned as bounces and appear in your bounce events. You may want to resend any time-sensitive messages that expired.

Thank you for your patience while Microsoft resolved this issue.