What is implicit and explicit email authentication failures in DMARC.

Question

What is implicit and explicit email authentication failures referring to below.

Answer 1

Hi,

As per MS Email Authentication in Exchange Online "Microsoft uses implicit email authentication to check inbound email".

Implicit email authentication is an extension of regular email authentication policies. These extensions include: sender reputation, sender history, recipient history, behavioral analysis, and other advanced techniques. In the absence of other signals from these extensions, messages sent from domains that don't use email authentication policies are marked as spoofing.

Check this link for detailed info on Implicit and Explicit - https://knowledge.validity.com/hc/en-us/articles/360040763112-What-is-Microsoft-s-anti-spoofing-protection-change-and-how-does-it-impact-me-

Hope this helps.

JS

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Answer 2

Hi @ Microsoft Q & A，

Explicit email authentication is the setting of SPF/DKIM/DMARC records against a domain to validate inbound email.

If a domain doesn't have traditional SPF, DKIM, and DMARC records, those record checks don't communicate enough authentication status information. Therefore, Microsoft has developed an algorithm for implicit email authentication.

Implicit email authentication is an extension of the general email authentication policy. These extensions include: sender reputation, sender history, recipient history, behavioral analytics, and other advanced technologies.

Please refer to this link for details:

Email authentication in Microsoft 365 | Microsoft Learn

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