Summary
Microsoft's composite authentication fails with DMARC set to 'p=none' primarily because Microsoft considers this a weaker form of email authentication. Even if SPF and DKIM checks pass, the 'p=none' policy signifies a lack of active enforcement against spoofing and phishing. This prompts Microsoft to use other signals to assess email legitimacy and may result in the email being flagged, marked as unverified, or sent to the junk folder. Experts and documentation alike advise transitioning to stricter DMARC policies, such as 'quarantine' or 'reject,' to improve domain reputation, increase email deliverability, and actively protect against unauthorized use of the domain. 'p=none' is primarily for monitoring and data collection but lacks the necessary enforcement to meet Microsoft's security expectations.
Key findings
- Weak Authentication: Microsoft considers DMARC 'p=none' a weaker authentication policy, potentially leading to composite authentication failure.
- No Enforcement: A DMARC policy of 'none' provides no enforcement against email spoofing and phishing, leaving the domain vulnerable.
- Microsoft's Interpretation: Microsoft may interpret 'p=none' as a lack of commitment to email security, leading to flags, unverified labels, or spam delivery.
- Transition Recommended: Experts and documentation recommend transitioning to stricter DMARC policies ('quarantine' or 'reject') for improved security and deliverability.
- Data Collection Only: 'p=none' primarily serves for monitoring and data collection, not active protection.
Key considerations
- Reputation Impact: Using 'p=none' can negatively impact domain reputation, potentially affecting how Microsoft treats emails from that domain.
- Long-Term Security: Implementing stricter DMARC policies is crucial for long-term email security and protection against unauthorized domain use.
- Combined Approach: Combining SPF, DKIM, and an enforced DMARC policy provides a more robust email security framework.
- Monitor and Adjust: DMARC implementation is an ongoing process. Continuously monitor DMARC reports and adjust the policy as needed to optimize deliverability and security.
- Email Authentication: Email Authentication in general, the setup and configuration is important to avoid being flagged as SPAM.
What email marketers say
8 marketer opinions
Microsoft's composite authentication may fail when DMARC is set to 'p=none' because this policy provides no enforcement against email spoofing and phishing. Although SPF and DKIM might pass, Microsoft views 'p=none' as a lack of commitment to strong email security, leading to flags, potential spam delivery, or 'unverified' labels. Microsoft uses additional signals to determine email legitimacy, and 'p=none' misses the opportunity to assert domain protection. Transitioning to 'quarantine' or 'reject' is generally recommended for improved security and deliverability.
Key opinions
- No Enforcement: DMARC 'p=none' instructs mail receivers to take no specific action on emails failing DMARC checks, providing no protection against spoofing.
- Microsoft Interpretation: Microsoft interprets 'p=none' as a lack of commitment to email security best practices, potentially causing composite authentication to fail.
- Additional Signals: Microsoft considers additional signals like sender reputation, content, and user complaints when determining email legitimacy.
- Transition Recommendation: Transitioning to stricter DMARC policies ('quarantine' or 'reject') is recommended for improved domain protection and deliverability.
Key considerations
- Impact on Deliverability: Using 'p=none' may not cause immediate deliverability issues but can leave your domain vulnerable and affect Microsoft's assessment of your email.
- Domain Reputation: A stricter DMARC policy can improve your domain's reputation, increasing the likelihood of emails being seen as legitimate by Microsoft.
- Comprehensive Protection: Combining SPF, DKIM, and DMARC enforcement provides more comprehensive email security than using 'p=none' alone.
- Gradual Implementation: Implementing DMARC is an ongoing process, and users should work up to 'Reject' policies.
Marketer view
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.
26 Jan 2025 - URIports Blog
Marketer view
Email marketer from EmailHippo mentions the importance of email authentication. They state that Microsoft may treat email from domains with DMARC 'none' policies differently.
27 Aug 2024 - EmailHippo
What the experts say
3 expert opinions
Microsoft composite authentication fails with DMARC set to 'p=none' because Microsoft explicitly considers it a weak authentication policy. It's not the absence of DMARC, but rather the choice to use 'p=none' that triggers the failure (compauth=fail reason=001). While not always causing immediate deliverability issues, it leaves the domain vulnerable to spoofing and phishing. Transitioning to a stricter DMARC policy ('quarantine' or 'reject') enhances domain reputation and improves Microsoft's perception of email legitimacy.
Key opinions
- Explicit Failure: Microsoft's composite authentication explicitly fails (compauth=fail reason=001) when DMARC is set to 'p=none'.
- Weak Policy: Microsoft considers 'p=none' a weak authentication policy, even if SPF and DKIM pass.
- Vulnerability: Using 'p=none' leaves the domain open to spoofing and phishing attacks.
- Reputation Improvement: Transitioning to a stricter DMARC policy can improve the domain's reputation and trustworthiness with Microsoft.
Key considerations
- Authentication vs. Deliverability: While 'p=none' might not always immediately impact deliverability, it impacts authentication status, leading to potential future issues.
- Policy Enforcement: Implementing 'quarantine' or 'reject' provides actual enforcement against unauthorized email use.
- Long-Term Security: Adopting a stricter DMARC policy is a proactive step towards enhancing long-term email security.
Expert view
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.
13 Sep 2021 - Word to the Wise
Expert view
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.
21 Apr 2022 - Email Geeks
What the documentation says
4 technical articles
Microsoft composite authentication may fail with a DMARC 'p=none' policy because it's considered a weaker form of authentication according to official documentation. While 'p=none' is useful for monitoring email authentication results, it does not provide active enforcement against unauthorized use of a domain. Official documentation encourages senders to transition to 'quarantine' or 'reject' policies for effective protection, impacting how systems like Microsoft treat the email. The DMARC standard (RFC7489) also implicitly suggests that enforcement policies are crucial for recipient mail systems to act decisively against unauthorized email. It's weaker when protecting against security threats.
Key findings
- Weaker Authentication: Microsoft Docs explicitly states that DMARC 'p=none' is considered a weaker form of authentication, leading to potential failure of composite authentication.
- Monitoring Purpose: DMARC.org indicates that 'p=none' is primarily for monitoring and gathering data, not for active protection.
- Lack of Enforcement: DMARC policies other than 'none' influence composite authentication results, hinting at 'p=none' being too weak against unauthorized emails.
- Not Strong: Google Admin points out that 'p=none' is not as strong when used against security threats and enforcement, making DMARC p=none emails treated with caution.
Key considerations
- Transition to Enforcement: Documentation advises senders to move to 'quarantine' or 'reject' policies for active prevention of unauthorized domain use and better compliance with systems like Microsoft.
- Data Collection vs. Protection: While 'p=none' allows for data collection, it doesn't offer the security benefits of more stringent DMARC policies.
- Industry Standards: Understanding industry standards like RFC7489 helps appreciate the importance of DMARC enforcement for email security.
Technical article
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.
28 Apr 2024 - Microsoft Docs
Technical article
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.
1 Feb 2024 - RFC Editor
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