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Microsoft Defender for Office 365 Blog
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Strengthening Email Ecosystem: Outlook’s New Requirements for High‐Volume Senders

Puneeth's avatar
Puneeth
Icon for Microsoft rankMicrosoft
Apr 02, 2025

This applies to Outlook.com - our consumer service, which is supporting hotmail.com live.com and outlook.com consumer domain addresses.

April 29th Update - Changes have been made to the action take on messages that do not meet requirements, please see details below. Introduction In an era where email remains one of the most widel...
Updated Apr 30, 2025
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JoelDS's avatar
JoelDS
Copper Contributor
Sep 05, 2025

Hi all, we ran into this error on a large scale at our organization. We were seeing higher than 40% bounce rate on emails sent to hotmail.com/msn.com/live.com/outlook.com from all mail sources, so we opened a ticket with Microsoft support (since we use M365 Exchange). They told us this is a known issue, and please submit a support request with Outlook.com Deliverability Support at olcsupport.office.com. We reached out and provided evidence of the errors. After some time, they told us they had allowlisted our domain. After that, the issue magically went away. Hope this helps somebody out there!