Summary
When transitioning a DMARC policy to p=reject, senders sometimes encounter unexpected email bounces, particularly with specific recipient mail security gateways like Symantec Email Security Cloud. This situation can be perplexing, as authentication and DMARC alignment might pass with all other providers, indicating a nuanced interaction or configuration issue specific to Symantec's platform. Understanding why these failures occur and how to address them requires a deep dive into how Symantec processes emails, especially its anti-phishing features which might modify email content, potentially breaking DKIM signatures and leading to DMARC alignment failures.
Key findings
- Specific platform issues: DMARC alignment failures with p=reject can be isolated to Symantec Email Security Cloud, even when other providers successfully authenticate the same emails.
- Content modification: Anti-phishing technologies often rewrite URLs within emails, which can invalidate DKIM signatures and cause DMARC authentication to fail. Learn more about debugging DMARC authentication failure.
- Tenant-level configuration: The issue might stem from specific recipient-side configurations within Symantec, rather than a general platform bug.
- Policy impact: Switching from p=quarantine to p=reject immediately causes bounces, while p=quarantine often results in delivery to the inbox or spam folder.
Key considerations
- Recipient engagement: Collaborating with a trusted recipient who uses Symantec Email Security Cloud can help escalate the issue through their support channels.
- Check for URL rewriting: Investigate if the receiving party has advanced anti-phishing or link protection services enabled that alter email content. Such services can lead to DMARC fail errors.
- Gradual policy implementation: Consider a phased approach for DMARC policy updates. You can learn how to transition your DMARC policy safely to quarantine or reject.
- Review Symantec settings: The issue might be a misconfiguration on the receiving side where Symantec's changes are not properly 'trusted' within their system.
What email marketers say
Email marketers frequently encounter DMARC challenges, especially when escalating to a p=reject policy. They often find themselves debugging issues that appear specific to certain recipient environments or email security gateways, even when their DMARC, SPF, and DKIM records are correctly configured and pass authentication with most providers. The primary frustration stems from the lack of transparency into how recipient systems like Symantec Email Security Cloud interact with and potentially modify incoming emails, leading to unexpected alignment failures and bounces.
Key opinions
- Inconsistent behavior: Marketers note that DMARC issues with Symantec are often isolated, not affecting all recipients on the platform, suggesting tenant-specific issues. This can cause legitimate emails to be blocked when DMARC policy is higher than p=none.
- Suspected content modification: Many suspect that anti-phishing technologies that rewrite URLs or alter email content are the root cause, breaking DKIM signatures and subsequently DMARC alignment.
- DMARC policy impact: It's observed that a p=quarantine policy delivers emails (even if to spam), while p=reject leads to outright bounces.
- Limited visibility: Marketers often lack direct access or expertise in recipient-side email security tools like Symantec, making troubleshooting difficult.
Key considerations
- Leverage recipient contacts: Working with a willing recipient to raise a support ticket with Symantec (or Broadcom) is often the most effective path for resolution.
- Understand email security features: Be aware that many email security solutions, including Symantec, Proofpoint, Barracuda, and Mimecast, employ optional add-on services like URL rewriting that can affect DMARC alignment. You can gain key insights from Symantec DMARC reports.
- Thorough testing: Before moving to p=reject, conduct extensive testing across a variety of major mailbox providers and email security gateways to identify potential issues. If emails are going to spam, check this guide for how to fix it.
Marketer view
Email marketer from Email Geeks suggests an odd issue where a sender updated their DMARC policy to p/sp=reject and are now seeing bounces with a handful of recipients who utilize Symantec Email Security Cloud citing DMARC alignment failures. This specific behavior is peculiar to Symantec.
Marketer view
Marketer from a Reddit forum states that their email authentication and DMARC alignment pass perfectly with all other providers after countless tests. The issue appears to be isolated to Symantec.
What the experts say
Email deliverability experts often highlight the complex interplay between DMARC policies and sophisticated email security solutions. They emphasize that while an organization may have correctly implemented DMARC, SPF, and DKIM, issues can arise due to the recipient's mail flow, particularly when security gateways modify emails in transit. These modifications, such as URL rewriting, can inadvertently break cryptographic signatures like DKIM, leading to DMARC alignment failures, especially under a strict p=reject policy. Experts typically recommend direct engagement with the recipient's IT team or security vendor support to diagnose and resolve these specific integration challenges.
Key opinions
- Systems integration issues: Experts suggest that DMARC failures with specific platforms like Symantec are often due to system integration problems or declining documentation/training standards, rather than sender misconfiguration.
- Recipient responsibility: The onus is often on the recipient to address issues arising from their email security setup. Engaging their support chain is crucial.
- URL rewriting impact: Anti-phishing technologies that rewrite URLs are a common culprit for breaking DKIM signatures, which then impacts DMARC alignment. You can find out more in this guide to demystifying DMARC.
- Trust configuration: Misconfiguration on the receiving side to properly 'trust' modifications made by their email security solution (e.g., Symantec) can lead to DMARC failures.
Key considerations
- Escalation via recipient: The most effective strategy is to have a friendly recipient contact Symantec (or Broadcom) support, as they have the direct relationship and tools to investigate tenant-specific issues.
- Bug vs. misconfiguration: Distinguishing between a Symantec bug and a specific tenant's misconfiguration is key. Symantec support would escalate true bugs, while misconfigurations need to be resolved by the tenant.
- Review mail flow: Understanding the entire mail flow path and any intermediary systems that process emails is essential. This can reveal where DKIM might be broken. Our guide on troubleshooting DMARC reject policies offers more steps.
- DMARC reporting analysis: Utilize DMARC aggregate and forensic reports to pinpoint exact authentication failures, the involved IPs, and the failing mechanisms (SPF or DKIM) to further diagnose. This is covered in our guide to DMARC reports.
Expert view
Expert from Email Geeks suggests that as a former channel partner, their advice for the sender is to pick a friendly recipient and ask them to raise the issue through their support chain at Symantec. This is often the most direct route.
Expert view
Expert from Spam Resource highlights that if the issue is indeed a bug within Symantec (now Broadcom), their support will escalate it accordingly. However, it's more likely a systems integration issue.
What the documentation says
Official documentation for DMARC (RFC 7489) outlines the policy's purpose in mitigating email abuse by allowing senders to indicate that their emails are protected by SPF and/or DKIM, and to tell receivers what to do if an email fails these authentication checks. However, specific vendor documentation, such as that from Symantec (now Broadcom), details their implementation of email security features, including anti-phishing, URL rewriting, and spam filtering. The challenge arises when these advanced security features, designed to protect recipients, inadvertently interfere with standard DMARC authentication processes by modifying the email in a way that breaks alignment.
Key findings
- DMARC policy application: DMARC policies like p=reject instruct receiving mail servers to bounce emails that fail DMARC authentication and alignment.
- DKIM sensitivity: DKIM is highly sensitive to changes in the email body or headers after signing. Any modification by an intermediate system will cause the DKIM signature to become invalid.
- Mail security gateway operations: Email security gateways, including Symantec, often implement URL rewriting, attachment stripping, or header modification as part of their security protocols.
- Alignment requirements: For DMARC to pass, either SPF or DKIM (or both) must align with the DMARC 'From' domain. If DKIM is broken, SPF alignment becomes critical for DMARC pass. Refer to this list of DMARC tags for more.
Key considerations
- Post-delivery processing: While DMARC checks occur at the mail server, additional post-delivery processing or internal email client security features could also affect perceived authentication.
- Vendor-specific configurations: Symantec's documentation often provides guidance on configuring trusted senders or bypassing certain security features for specific domains, which could be relevant here.
- Standard vs. custom: DMARC works based on standardized protocols, but how security products integrate these standards with their proprietary features can vary. For example, DMARC record and policy examples should always be followed.
- Monitoring DMARC reports: Regularly analyzing DMARC aggregate reports can reveal patterns of authentication failures and help identify specific receivers causing issues, guiding further investigation.
Technical article
Technical documentation from Symantec/Broadcom explains that their Email Security Cloud solution incorporates advanced threat protection features, including link protection and attachment sandboxing, which involve rewriting URLs and analyzing content for malicious intent.
Technical article
RFC 7489 (DMARC) states that DMARC processing relies on the integrity of SPF and DKIM authentication. Any alteration of email content or relevant headers by intermediate agents can result in authentication failure, leading to policies like p=reject being enforced.
Related resources
4 resources
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