Outage in Tessian EU
Outlook for Mac - Email Send blocked for some users
Resolved Minor
January 15, 2026 - Started 19 days ago
- Lasted about 1 hour
Incident Report
We've been made aware of a Microsoft issue affecting all OnSend Office Add-ins within Outlook for Mac, which prevents users from sending emails.
This issue seems to be triggered after restarting Outlook for Mac, and first impact was reported around 21:00 UTC Jan 14th 2026.
OWA, Classic Outlook on PC, and New Outlook on PC are not impacted. This appears to be specific to the Outlook for Mac client.
If this is impacting your users we recommend them to send emails via Outlook on the Web (OWA) until Microsoft release a resolution.
We have escalated the issue to Microsoft and are awaiting further information, including a fix timeline and details.
We will update as more information becomes available.
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Latest Updates ( sorted recent to last )
IDENTIFIED
19 days ago - at 01/15/2026 04:29PM
Proofpoint has been notified by Microsoft that they've made some updates to address the issue.
They recommended impacted users restarting Outlook for Mac and confirm if they can send emails again.
Proofpoint has verified this has resolved the issue for some, but not yet all users via testing.
We are also awaiting additional details from Microsoft as the specific cause and what they fixed to resolve it.
IDENTIFIED
19 days ago - at 01/15/2026 04:18PM
We've been made aware of a Microsoft issue affecting all OnSend Office Add-ins within Outlook for Mac, which prevents users from sending emails.
This issue seems to be triggered after restarting Outlook for Mac, and first impact was reported around 21:00 UTC Jan 14th 2026.
OWA, Classic Outlook on PC, and New Outlook on PC are not impacted. This appears to be specific to the Outlook for Mac client.
If this is impacting your users we recommend them to send emails via Outlook on the Web (OWA) until Microsoft release a resolution.
We have escalated the issue to Microsoft and are awaiting further information, including a fix timeline and details.
We will update as more information becomes available.
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