Why does Microsoft composite authentication fail with DMARC p=none?

Email marketer from URIports Blog shares that Microsoft will still look at other signals, such as sender reputation, content, and user complaints, to determine the legitimacy of an email. A DMARC policy of 'none' is a missed opportunity to explicitly tell Microsoft that you are taking steps to protect your domain.

Email marketer from EmailHippo mentions the importance of email authentication. They state that Microsoft may treat email from domains with DMARC 'none' policies differently.

Email marketer from Mailhardener Blog shares that using DMARC with a policy of `p=none` essentially tells Microsoft 365 to take no specific action based on DMARC results. While it allows you to collect reports, it doesn't provide any protection against spoofing, and Microsoft may still flag emails due to the lack of a strict DMARC policy.

Email marketer from Reddit shares personal experience noting that even with valid SPF and DKIM records, Microsoft's systems sometimes flag emails as unverified if DMARC is set to `p=none`. They recommend transitioning to a stricter DMARC policy.

Email marketer from EasyDMARC explains that setting your DMARC policy to 'none' provides no enforcement. Microsoft, and other email providers, may still use their own criteria for filtering, and a 'none' policy might not be sufficient to prevent messages from being flagged. Transitioning to 'quarantine' or 'reject' is essential for full protection.

Email marketer from EmailSecurityATP discusses Microsoft's interpretation of DMARC. They state that Microsoft considers senders with `p=none` not fully protected. They say the senders should gradually move to `quarantine` or `reject` to have a full anti-spoofing protection.

Email marketer from PostmarkApp explains that a DMARC policy of `p=none` instructs mail receivers to take no action regarding messages that fail DMARC authentication. This policy does not provide any protection against spoofing and phishing attacks, which is why email providers like Microsoft might flag your emails or deliver them to the spam folder.

Email marketer from StackExchange explains that Microsoft may interpret a `p=none` policy as a sign that the sender is not fully committed to email security best practices, causing composite authentication to fail even when other authentication checks pass. The user advises to move to a stricter policy.

Expert from Word to the Wise forum explains that while a DMARC policy of p=none won't directly cause deliverability issues in all cases, it does leave your domain open to potential spoofing and phishing attacks. They suggest that transitioning to a more restrictive policy like p=quarantine or p=reject will help to improve your domain's reputation and increase the likelihood that Microsoft will view your emails as legitimate.

Expert from Email Geeks explains that using `p=none` in DMARC is explicitly causing a `compauth=fail reason=001` in Microsoft's composite authentication. Microsoft considers `p=none` a weaker authentication policy, leading to the failure.

Expert from Email Geeks clarifies that the problem is not the lack of DMARC, but using DMARC with a policy of `p=none`, which is sufficient to trigger the failure in Microsoft's authentication process.

Documentation from Microsoft Docs explains that when DMARC is set to `p=none`, it's considered a weaker form of authentication. Consequently, Microsoft's composite authentication may fail, resulting in messages being marked as 'Not verified' or potentially ending up in the junk folder, even if SPF and DKIM pass.

Documentation from RFC Editor (RFC7489) describes the DMARC standard. It implicitly indicates that enforcement (policies other than 'none') is crucial for recipient mail systems to act decisively against unauthorized email, influencing composite authentication results.

Documentation from Google Admin says DMARC policies specify how recipient servers should handle email messages that fail DMARC checks. The 'none' policy is recommended to monitor your email flow without affecting delivery. It's not as strong when used against security threats and enforcement.

Documentation from DMARC.org explains that a DMARC policy of 'none' is primarily for monitoring and gathering data on email authentication results. It advises that senders should eventually move to 'quarantine' or 'reject' policies to actively prevent unauthorized use of their domain, which directly impacts how systems like Microsoft's treat email.