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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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ats310's avatar
ats310
Copper Contributor
Apr 16, 2025

Hi Puneeth ,
I have a question.

 

The email delivery service I'm currently using doesn't have a Reply-To header set, only a Return-Path header. If the sender sends a "no-reply" email through this service (the address is RFC-compliant, but doesn't exist), how will this guideline be evaluated?

I would like to know if a correctly set Return-Path header is evaluated equally to the From and Reply-To headers.