Outage in Fastmail
Microsoft update misclassifying Fastmail emails to Outlook addresses
Minor
January 27, 2026 - Started 7 days ago
Incident Report
A recent Microsoft update is sometimes incorrectly flagging some emails from several providers, including Fastmail. This is causing intermittent delivery issues for some email sent to addresses hosted on [outlook.com](http://outlook.com). We are seeing a small percentage of outgoing mail affected, with no obvious reason as to why. Our team is actively working with Microsoft's email team to get this resolved as soon as possible.
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Latest Updates ( sorted recent to last )
IDENTIFIED
7 days ago - at 01/27/2026 04:30AM
A recent Microsoft update is sometimes incorrectly flagging some emails from several providers, including Fastmail. This is causing intermittent delivery issues for some email sent to addresses hosted on [outlook.com](http://outlook.com). We are seeing a small percentage of outgoing mail affected, with no obvious reason as to why. Our team is actively working with Microsoft's email team to get this resolved as soon as possible.
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