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Why are mailto: unsubscribe emails from Laposte.net failing DMARC authentication?

Summary

Emails sent via the mailto:unsubscribe mechanism from Laposte.net are encountering DMARC authentication failures. This issue primarily stems from a misconfiguration involving an intermediary service, Vade, which handles these unsubscribe requests. The problem arises because Vade's sending IP address is not authorized in Laposte.net's SPF record, and there appears to be no valid DKIM signature that aligns with the From domain. Given Laposte.net's DMARC policy is set to p=quarantine, these authentication failures lead to the emails being junked or rejected, causing significant compliance and deliverability challenges for recipients who are legally required to honor unsubscribe requests. Understanding how DMARC works is crucial for resolving such complex authentication issues, particularly when third-party services are involved in the email flow. For more details on DMARC authentication, consider reviewing a simple guide to DMARC, SPF, and DKIM.

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What email marketers say

Email marketers often face complex authentication challenges, especially when dealing with transactional emails or specialized services like unsubscribe mechanisms. The general sentiment among marketers encountering DMARC failures for critical mail flows, such as those from mailto:unsubscribe links, is one of concern regarding compliance and deliverability. They recognize the immediate impact on sender reputation and the potential legal repercussions of not honoring unsubscribe requests. The frustration often stems from relying on third-party vendors whose authentication setups may not fully align with the sender's DMARC policy, leading to unexpected failures. For more on improving deliverability, explore ultimate email deliverability guides.

Marketer view

Email marketer from Email Geeks observes unsubscribe emails from Laposte.net are failing authentication. They note that a specific IP address (185.187.30.19) used by Vade is not in Laposte.net's SPF record, and their DMARC policy is set to quarantine.

28 Apr 2019 - Email Geeks

Marketer view

Email marketer from WebmasterWorld highlights that misconfigured DMARC policies can significantly hinder legitimate email delivery, even for crucial communications like unsubscribe requests. They advise regular checks of DMARC reports to spot such anomalies quickly.

15 May 2023 - WebmasterWorld

What the experts say

Email deliverability experts focus on the technical root causes of DMARC failures and the strategic implications for email senders. When faced with an issue like Laposte.net's unsubscribe emails failing DMARC, their analysis centers on the authentication chain: SPF, DKIM, and DMARC alignment. They typically look for missing or incorrect SPF records for third-party senders, unaligned DKIM signatures, and the overall impact of the DMARC policy (e.g., p=quarantine). Experts also consider the context, such as special MX records for handling specific email types, and the potential for a false positive or a useless attack vector. It is important to remember that even if DMARC authentication fails when SPF and DKIM pass, there are still ways to troubleshoot. For additional insights on email deliverability, consult comprehensive email delivery guides.

Expert view

Expert from Email Geeks finds the situation interesting and states his intention to investigate further by contacting the relevant parties. This proactive approach is typical of deliverability experts.

09 Sep 2019 - Email Geeks

Expert view

Expert from SpamResource.com states that a common reason for DMARC failure with third-party senders is an SPF record that does not authorize the specific sending IP address. They recommend reviewing the SPF record and adding any missing IPs to ensure alignment.

12 Apr 2024 - SpamResource.com

What the documentation says

Official documentation and internet standards (RFCs) provide the foundational rules for email authentication, including SPF, DKIM, and DMARC. They define how domains should authorize sending sources and how receiving mail servers should process emails based on authentication results. A key principle is that for DMARC to pass, an email must pass either SPF or DKIM authentication, and the authenticating domain must align with the From header domain. Failures often indicate a breach of these defined standards, usually due to misconfiguration rather than inherent flaws in the protocols themselves. For more on the standards, consider resources on deploying DMARC for email reception.

Technical article

RFC 7489 (DMARC) states that for an email to pass DMARC, it must either pass SPF authentication with alignment of the SPF domain to the From header domain, or pass DKIM authentication with alignment of the DKIM domain to the From header domain.

08 Mar 2015 - RFC 7489

Technical article

RFC 7208 (SPF) outlines that an SPF record specifies which hosts are authorized to send mail for a domain. If an email is sent from an IP address not listed in the SPF record, it will typically result in an SPF fail.

17 Apr 2014 - RFC 7208

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