Microsoft outage: delays delivering to Outlook, Hotmail and Office 365
Incident
Report for Bird
Resolved
Microsoft has confirmed an incident affecting Exchange Online and Microsoft 365 connectivity in all regions. It’s tracked as EX1550543, and you can follow Microsoft’s updates at https://status.cloud.microsoft/m365/referrer=serviceStatusRedirect.
Since about 17:30 UTC on November 12, Microsoft’s mail servers have been answering a large share of delivery attempts with temporary errors. This affects Outlook.com, Hotmail, Live, MSN and Office 365 recipients. The errors include “451 4.7.0 Temporary server error”, “421 4.3.2 The maximum number of concurrent server connections has exceeded a limit” and “451 4.7.700 PFA agent busy”. The problem is on Microsoft’s side and affects senders across the industry. SparkPost’s own systems are working normally.
Affected messages are not lost. SparkPost queues them and keeps retrying automatically, and many are already going through on a retry. You’ll see these attempts as delay events in your event data. Recipients at Microsoft may get mail later than usual until Microsoft resolves EX1550543. Delivery to other mailbox providers is not affected.
You don’t need to do anything, and please don’t send these messages again. Resending creates duplicates once the queued mail goes through. If you’ve set a short message expiration (for example on one-time passcodes), those messages may expire before Microsoft recovers.
We’re watching this closely and will post an update as soon as things change.
Since about 17:30 UTC on November 12, Microsoft’s mail servers have been answering a large share of delivery attempts with temporary errors. This affects Outlook.com, Hotmail, Live, MSN and Office 365 recipients. The errors include “451 4.7.0 Temporary server error”, “421 4.3.2 The maximum number of concurrent server connections has exceeded a limit” and “451 4.7.700 PFA agent busy”. The problem is on Microsoft’s side and affects senders across the industry. SparkPost’s own systems are working normally.
Affected messages are not lost. SparkPost queues them and keeps retrying automatically, and many are already going through on a retry. You’ll see these attempts as delay events in your event data. Recipients at Microsoft may get mail later than usual until Microsoft resolves EX1550543. Delivery to other mailbox providers is not affected.
You don’t need to do anything, and please don’t send these messages again. Resending creates duplicates once the queued mail goes through. If you’ve set a short message expiration (for example on one-time passcodes), those messages may expire before Microsoft recovers.
We’re watching this closely and will post an update as soon as things change.