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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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r1ch97rd's avatar
r1ch97rd
Copper Contributor
Jun 19, 2025

Hi Puneeth, I'm the email admin for the university, we encountered the error "5.7.515 Access denied" due to DKIM = Fail since Jun 17, 2025. However, the Spf=Pass and DMARC=Pass are not honored by Microsoft. Why DMARC is not honored at Microsoft? And we have corrected the DKIM issue the same day. The messages sent to gmail recipients shows SPF/DKIM/DMARC all pass, however, we still get bounce from Microsoft email domains with the same error after a day. I guess there's something (blacklist, or DNS cache) on Microsoft email system to be refreshed.