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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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aleeri's avatar
aleeri
Copper Contributor
Sep 11, 2025

This is really causing issues! I have contacted MS support for whitlisting. We are using Sendgrid with a dedicated IP.

All SPF, DKIM, DMARC are fine and aligned. Still we experience SPF=fail on random emails to Microsoft Office 365 recipients.

The sender's domain in the 5322.From address doesn't meet the authentication requirements defined for the sender. To learn how to fix this see: https://go.microsoft.com/fwlink/p/?linkid=2319303 Spf= Fail , Dkim= Pass , DMARC= Pass