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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
Version 4.0
awareness & training
email protection basics
rsetht's avatar
rsetht
Copper Contributor
Jun 20, 2025

We've begun receiving 5.7.515 errors showing "Dkim= Fail".  Every tester I've run our email through shows DKIM passing completely.  All domains in the header match the sending domain.   Any help?

sysguru2046's avatar
sysguru2046
Copper Contributor
Jun 20, 2025

same here

  • rsetht's avatar
    rsetht
    Copper Contributor
    Jun 20, 2025

    Please let me know if you get a resolution.  I'll post here, as well, if I find something.