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Microsoft Defender for Office 365 Blog
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Strengthening Email Security: Our New Approach to Non-RFC Compliant Emails

Puneeth's avatar
Puneeth
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Mar 17, 2025
In our ongoing commitment to enhance email security and protect our users from malicious activities, we are making changes in handling emails with non RFC-compliant  P2Sender addresses. This change r...
Updated Mar 17, 2025
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ajanes-arc's avatar
ajanes-arc
Iron Contributor
Mar 18, 2025

This article mentions the use of RFCs to determine whether or not the from header is compliant. Can you point to the exact RFCs you are utilizing to setup this determination? Is it just RFC5322? Or is it more than that?

Puneeth's avatar
Puneeth
Icon for Microsoft rankMicrosoft
Mar 25, 2025

It's RFC 5322 and RFC 6854.