Outbound Mail Delivery: Rejections for Some Microsoft 365 / Outlook Recipients

This incident has been resolved. Any messages that bounced during the incident can continue to be resent.

We are seeing further reports of outbound emails to Microsoft 365 and Outlook recipients being rejected. The issue is ongoing and our engineering team is continuing to work with Microsoft and our email delivery provider on a resolution.

Inbound mail remains unaffected. Bounced messages were not lost and can be resent once delivery is restored.

The issue has been mitigated. We are monitoring closely and continuing to work with Microsoft. Any messages that bounced during the incident can now be resent.

We are seeing further reports of outbound emails to Microsoft 365 and Outlook recipients being rejected. The issue is ongoing and our engineering team is continuing to work with Microsoft and our email delivery provider on a resolution.

Inbound mail remains unaffected. Bounced messages were not lost and can be resent once delivery is restored.

The issue has been mitigated. We are monitoring closely and continuing to work with Microsoft. Any messages that bounced during the incident can now be resent.

We are investigating an issue affecting outbound email from Sedna to recipients hosted on Microsoft 365 and Outlook. Microsoft's anti-spam filtering is rejecting messages sent from a number of our outbound IP addresses, and senders are receiving bounce-back notifications (NDRs) for affected messages.

Inbound mail is not affected, and delivery to recipients outside of Microsoft 365 / Outlook is unaffected.

We will provide further updates as our investigation progresses.