How does XS4ALL handle DMARC enforcement and DKIM signatures?

Summary

XS4ALL employs a unique DMARC enforcement strategy where they prioritize DKIM signatures. If an email lacks DKIM, even with an SPF-backed DMARC policy set to 'reject' or 'quarantine,' XS4ALL might treat it as 'p=none,' effectively ignoring the sender's requested policy. This approach aims to balance security with deliverability, preventing legitimate forwarded emails from being incorrectly rejected due to SPF limitations. Experts and documentation emphasize the importance of using both SPF and DKIM for DMARC, highlighting DKIM's robustness during email forwarding. XS4ALL's public stance is seen as a positive step towards promoting transparency and encouraging proper email authentication practices. This also encourages senders to ensure DKIM is properly configured or risk deliverability issues and potential negative impacts on domain reputation.

Key findings

  • DKIM Prioritization: XS4ALL prioritizes DKIM signatures for DMARC enforcement.
  • Policy Modification: They might treat DMARC 'reject' or 'quarantine' policies as 'none' if DKIM is missing.
  • SPF Limitations: Relying solely on SPF for DMARC at XS4ALL is insufficient due to forwarding issues.
  • Deliverability Balance: Their approach balances email security with maintaining email deliverability.
  • Transparency Benefit: Publicly stating this policy is considered a positive step.
  • Domain Reputation Impact: Lacking DKIM can negatively impact domain reputation.

Key considerations

  • Implement DKIM: Ensure DKIM is properly configured to avoid potential DMARC enforcement issues with XS4ALL.
  • SPF/DKIM Setup: Setup both SPF and DKIM correctly as a prerequisite for DMARC.
  • Test Authentication: Thoroughly test SPF and DKIM records before implementing a DMARC policy.
  • Forwarding Concerns: Consider the impact of email forwarding when implementing SPF-only policies.
  • Monitor Reputation: Monitor your domain reputation to ensure no negative impact.

What email marketers say
9Marketer opinions

XS4ALL prioritizes DKIM signatures in their DMARC enforcement. If an email lacks DKIM, they may treat a reject policy as 'none,' particularly when relying solely on SPF. This approach aims to balance security and deliverability, preventing legitimate forwarded emails from being incorrectly rejected due to SPF failures. By favoring DKIM, XS4ALL encourages senders to implement more robust authentication methods, benefitting the overall email ecosystem and making the internet safer.

Key opinions

  • DKIM Priority: XS4ALL prioritizes DKIM signatures over SPF alone for DMARC enforcement.
  • Policy Override: They might treat DMARC 'reject' policies as 'none' if DKIM is missing to avoid rejecting forwarded emails.
  • Balance Security: XS4ALL's strategy balances email security with ensuring deliverability.
  • Forwarding Issues: Relying solely on SPF is risky due to forwarding compatibility issues, which XS4ALL mitigates.
  • Ecosystem Benefit: Encouraging DKIM implementation improves the overall email security ecosystem.

Key considerations

  • Implement DKIM: Senders should implement DKIM to ensure their emails are properly authenticated with XS4ALL.
  • SPF Alone is Insufficient: Relying on SPF alone might not be sufficient for DMARC compliance with XS4ALL, potentially leading to deliverability issues.
  • Monitor Reputation: Pay attention to domain reputation, as lack of DKIM could negatively impact it.
  • Test Configuration: Test your DMARC, SPF and DKIM records to ensure they are valid and working correctly.
Marketer view

Email marketer from Reddit explains that some providers, like XS4ALL, might treat DMARC policies with p=reject as p=none if DKIM is not implemented. This is because relying solely on SPF can lead to false positives with forwarding.

April 2021 - Reddit
Marketer view

Email marketer from Mailhardener Blog explains that while not explicitly stated, XS4ALL likely prioritizes DKIM because it survives forwarding, and SPF often breaks upon forwarding. It's a common practice for receivers to be more lenient when DKIM is present.

March 2021 - Mailhardener Blog
Marketer view

Email marketer from MXToolbox Support details that while DMARC can technically work with only SPF, it is highly recommended to use DKIM alongside it for better authentication and deliverability. XS4ALL's actions reinforce this recommendation.

February 2024 - MXToolbox
Marketer view

Email marketer from GMass explains that XS4ALLs policy promotes better overall security by encouraging people to use DKIM. It provides an extra layer of authentication for their email deliverability.

November 2023 - GMass
Marketer view

Email marketer from Email Geeks shares that domain reputation seems to feed negatively when DKIM is lacking.

October 2024 - Email Geeks
Marketer view

Email marketer from Superuser Forum suggests that XS4ALL is encouraging best practices by prioritizing DKIM. They believe this makes the internet a slightly safer place. It encourages correct setup.

August 2023 - Superuser Forum
Marketer view

Email marketer from Quora points out that relying only on SPF for DMARC is risky because SPF is easily broken by forwarding. XS4ALL's policy is a way to mitigate these risks for their users.

April 2022 - Quora
Marketer view

Email marketer from StackExchange explains that XS4ALL’s approach encourages senders to properly implement DKIM, which is the more reliable authentication method. This benefits the overall email ecosystem.

June 2021 - StackExchange
Marketer view

Email marketer from EmailSecurityAnswers Forum shares that XS4ALL's approach prevents legitimate forwarded emails from being rejected due to SPF failures. They suggest it's a pragmatic approach, balancing security and deliverability.

April 2024 - EmailSecurityAnswers Forum

What the experts say
4Expert opinions

XS4ALL employs a specific DMARC enforcement strategy where they won't reject emails for DMARC failure if DKIM signatures are absent, even if SPF is in place with a reject policy. They treat such emails as 'p=none,' effectively ignoring the reject instruction. Experts highlight the importance of publishing DMARC records and recommend configuring DKIM alongside SPF due to DKIM's resilience during email forwarding, unlike SPF. Publicly disclosing this approach is seen as a positive step by XS4ALL, promoting transparency and encouraging senders to implement proper email authentication practices.

Key opinions

  • DKIM Requirement: XS4ALL does not strictly enforce DMARC reject/quarantine policies when DKIM is missing.
  • SPF Inadequacy: Relying solely on SPF for DMARC is insufficient at XS4ALL.
  • Transparency: XS4ALL's public declaration of their DMARC handling is a welcome practice.
  • Forwarding Considerations: DKIM is preferred due to its ability to survive email forwarding.

Key considerations

  • Implement DKIM: Ensure DKIM is properly configured when sending emails to XS4ALL recipients.
  • DMARC Record: Publish a DMARC record regardless of reliance on SPF, preferrably alongside DKIM.
  • Testing: Thoroughly test DKIM records before implementation.
Expert view

Expert from Email Geeks responds that it’s mostly nice that they’re publicly saying “hey, y’all, we’re doing the smart thing” rather than silently doing the smart thing.

November 2024 - Email Geeks
Expert view

Expert from Email Geeks explains that DMARC enforcement at XS4ALL is interesting because they will not reject for DMARC failure if there is no DKIM signature. If you’re relying on SPF for DMARC and you have a quarantine or reject policy, they ignore any policy statements and treat it as p=none. (based on a statement from them on mailop)

June 2024 - Email Geeks
Expert view

Expert from Word to the Wise recommends configuring DKIM alongside SPF for DMARC implementation. They mention that DKIM survives forwarding while SPF often breaks when forwarding email. They recommend testing your DKIM records before implementing them.

March 2023 - Word to the Wise
Expert view

Expert from Spam Resource explains that it is important to publish a DMARC record even if you think you are only using SPF for authentication. Using DKIM with DMARC can lead to an improvement in email deliverability and reduce issues.

April 2021 - Spam Resource

What the documentation says
5Technical articles

Documentation indicates that XS4ALL strongly encourages the use of DMARC with both SPF and DKIM for email spoofing protection. DMARC.org highlights DKIM as a robust authentication method that persists through email forwarding, addressing SPF's forwarding limitations. The DMARC standard (RFC 7489) allows receivers flexibility in policy enforcement, aligning with XS4ALL's practices. Major platforms like Google Workspace and Microsoft emphasize that both SPF and DKIM are essential for DMARC's effective function, providing comprehensive email security.

Key findings

  • Encouraged DMARC: XS4ALL encourages DMARC use for email spoofing protection.
  • SPF & DKIM: Setting up both SPF and DKIM is advised as a prerequisite for DMARC.
  • DKIM Robustness: DKIM persists through forwarding, unlike SPF.
  • Policy Flexibility: DMARC standards allow receivers to ignore sender policies.
  • Essential Protocols: SPF and DKIM are essential for DMARC's effective function.

Key considerations

  • Implement Both: Implement both SPF and DKIM for robust DMARC protection.
  • Address Forwarding: Understand SPF's limitations with email forwarding and leverage DKIM.
  • Receiver Flexibility: Be aware that receivers may not always strictly enforce DMARC policies.
  • Comprehensive Security: Employ both SPF and DKIM for comprehensive email security.
Technical article

Documentation from RFC 7489, the official DMARC standard, specifies that receivers can choose to ignore the sender's DMARC policy under certain circumstances. XS4ALL's behavior aligns with this flexibility allowed in the standard.

March 2021 - RFC Editor
Technical article

Documentation from DMARC.org highlights that DMARC relies on SPF and DKIM. While SPF can have issues with forwarding, DKIM provides a robust authentication method that persists even when an email is forwarded, making it a crucial component of a DMARC setup.

April 2023 - DMARC.org
Technical article

Documentation from Google Workspace Admin Help emphasizes that both SPF and DKIM are essential for DMARC to function effectively, providing comprehensive protection against email spoofing and phishing. Google recommends using both.

August 2022 - Google Workspace Admin Help
Technical article

Documentation from XS4ALL Support Pages explains that they strongly encourage the use of DMARC to protect against email spoofing. They advise setting up SPF and DKIM correctly as a prerequisite for DMARC.

August 2023 - XS4ALL Support Pages
Technical article

Documentation from Microsoft explains that DMARC uses SPF and DKIM to verify the authenticity of email messages and provides instructions for configuring these protocols to enhance email security and prevent spoofing. While they do not comment specifically on XS4ALL it is a general view.

February 2024 - Microsoft Documentation