DMARC Reports: Debunking Privacy Myths and Minimizing Risk

Domain-based Message Authentication, Reporting, and Conformance (DMARC) is an essential email authentication protocol designed to protect your domain from being used in phishing and spoofing attacks. 

One of DMARC’s core features is its ability to generate reports that provide valuable insights into who is sending emails on behalf of your domain. However, some organizations are hesitant to enable DMARC reporting due to concerns about sharing potentially sensitive data with third parties. This article aims to dispel misconceptions about DMARC reporting, clarify what information is actually shared, and provide practical guidance on how to minimize privacy risks.

Understanding DMARC Reports

DMARC generates two types of reports:

1. Aggregate Reports (RUA) - These reports provide a high-level overview of email authentication results, including metadata such as sending IP addresses, domain alignment, and the DMARC policy applied. They are sent to the address specified in the "rua" tag of your DMARC record.
2. Forensic Reports (RUF) - These reports, also known as failure or message-specific reports, contain more detailed information, including message headers, and in some cases, subject lines and content. They are sent to the address specified in the "ruf" tag.

Who Generates the Reports?

A common misconception is that sending DMARC reports involves your email server transmitting data to third parties. In reality, it is the receiving email server that generates these reports. When your domain sends an email to another server (like Gmail or Outlook), that server checks your DMARC policy and, if configured, generates a report based on the result of that check. Therefore, your organization has no control over whether a receiving server generates these reports once your policy requests them.

Aggregate vs. Forensic Reports

While both report types serve to increase visibility into your domain’s email traffic, they differ significantly in terms of privacy implications:

Aggregate Reports (RUA)

• Generated regardless of DMARC outcome (pass or fail).
• Contain only metadata and no email content, making them relatively safe from a privacy perspective.
• Typically sent daily and in XML format.

Forensic Reports (RUF)

• Generated only when a message fails DMARC checks.
• May include potentially sensitive information, such as message headers and even parts of the email body.
• Not all receiving servers generate forensic reports—many have opted not to, due to privacy and compliance concerns.
• The default behavior is to generate forensic reports only on DMARC failures.

Minimizing Privacy Risks

The best way to mitigate privacy risks is to limit which reports you request in your DMARC policy:

1. Exclude Forensic Reports (RUF) - Simply omit the "ruf" tag from your DMARC record to ensure no forensic data is collected or shared.

   Example DMARC record without RUF:

   v=DMARC1; p=reject; rua=mailto:dmarc-reports@yourdomain.com
   

2. Use Trusted Email Reporting Services - If you do use RUF, consider configuring it to send to a trusted third party or internal system that is designed to securely manage sensitive data.

3. Review Privacy Policies of Receiving Servers - Understand that the vast majority of servers do not generate forensic reports at all, and those that do typically redact or minimize content to protect privacy.

Final Thoughts

For organizations new to DMARC, the potential risks around RUF reports can seem daunting. However, the reality is that the vast majority of DMARC data shared is aggregate metadata that poses little to no risk of exposing sensitive content. By configuring your DMARC record carefully and opting only for RUA reports, you can significantly minimize your privacy exposure while still gaining valuable insights into email authentication.

Have questions or need more guidance on implementing DMARC? Reach out to a trusted expert to ensure your email domain is protected while maintaining privacy best practices.