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Outage in SparkPost

Delays in sending emails to Microsoft domains

Minor
January 15, 2026 - Started 4 days ago
Official incident page

Incident Report

We are currently investing reported delays when sending emails towards Microsoft email domains

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Latest Updates ( sorted recent to last )
MONITORING about 4 hours ago - at 01/19/2026 06:18PM

We continue to see improvement with Microsoft delivery, though isolated cases of delays persist. Microsoft's mitigations are largely effective, but we're still working with their team to address edge cases as they arise. We will continue to maintain heightened monitoring through the week to ensure complete stabilization. No action is required from senders - any affected messages will continue to retry automatically.

MONITORING 2 days ago - at 01/17/2026 11:30PM

We have seen stabilization, but are still seeing Microsoft delays in rare cases. Our team is mitigating with Microsoft as those occur. We are going to keep the status page in Monitoring state through the weekend as we continue to monitor for a full recovery at Microsoft.

IDENTIFIED 3 days ago - at 01/16/2026 04:03PM

We continue to see some delays at Microsoft domains and are working with Microsoft to remediate. At this time, Microsoft is aware and continues to investigate.

IDENTIFIED 4 days ago - at 01/15/2026 01:49PM

We have started to receive reports from Microsoft that they are implementing mitigations within their environment. We continue to monitor and coordinate with them for full resolution.

IDENTIFIED 4 days ago - at 01/15/2026 01:25PM

We continue to work with Microsoft on these delays. We are in active contact with their delivery team and working towards full resolution.

INVESTIGATING 4 days ago - at 01/15/2026 11:50AM

Microsoft continues to investigate the issue. We are actively in contact with their team.

INVESTIGATING 4 days ago - at 01/15/2026 11:13AM

We continue to work with Microsoft on full mitigation. They are currently experiencing infrastructure issues that is causing them to incorrectly block legitimate traffic from multiple Bird IP ranges.

Our sending infrastructure and email traffic are operating normally. All other mailbox providers are receiving mail without issue.
Microsoft is aware of the issue and is actively investigating. We are in contact with their team and monitoring for resolution.
We expect this to be resolved once Microsoft completes their fix.

Messages will retry automatically - no action needed from you

INVESTIGATING 4 days ago - at 01/15/2026 11:06AM

Impact is confirmed to be scoped to EU region only.
Investigation ongoing; tickets raised to Microsoft to further investigation.

INVESTIGATING 4 days ago - at 01/15/2026 10:24AM

We are currently investing reported delays when sending emails towards Microsoft email domains

Latest SparkPost outages

Delay in event processing. - about 1 month ago
Longer than expected delays - about 1 month ago
Data processing delays - about 1 month ago

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