Delayed or failed email delivery to Microsoft sender addresses

Following comprehensive monitoring, we can confirm that the incident has been fully resolved and all services have returned to normal operation.

Emails to Microsoft business mailboxes are being accepted again, with new notifications going through normally.

The emails held up during the incident are still being sent out by our provider, which reports around 40% of them left to deliver. Until that backlog is cleared, recipients may still receive notifications with a delay. Nothing is lost, and you do not need to send anything again.

We will provide a further update once the backlog is fully delivered.

This issue has been identified by our suppliers delivery providers, and they are in contact to find a resolution for this issue. Personal Microsoft accounts (outlook.com, hotmail.com, live.com) are not affected, and no other email provider is impacted. This issue is specific to Microsoft 365 and Exchange Online business mailboxes.

Due to the nature of the fault, the supplier is unable to commit to a firm resolution time. We're tracking progress closely with our providers.

Once the issue clears, we'll confirm whether emails held since this morning are delivered automatically or need to be resent.

We will provide an update within the next hour, or as soon as one is made available to us.

Some emails sent to Microsoft-hosted addresses (Outlook, Hotmail, Live and Microsoft 365) are arriving late or not at all.

The suppliers own delivery tracking shows that every email is still being accepted by their sending providers, so the problem appears to occur after that hand-off. They are investigating with them to confirm the cause. Emails to all other providers are unaffected.

No action is required on your side.

We will post a new update as soon as we know more, and we are sorry for the disruption this is causing.

We have detected potential service disruption through our monitoring systems and are actively investigating. A detailed assessment of the impact and affected services will be provided within the next 30 minutes.