Handling DMARC Fails with SPF and DKIM Passes on Mail Servers

Handling DMARC Fails when SPF and DKIM Pass on a Different Mail Server

Email authentication is crucial to prevent spoofing and phishing attacks. DMARC (Domain-based Message Authentication, Reporting, and Conformance) is an email authentication protocol that builds on the SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) protocols. However, when an email is sent from a different mail server than the one receiving it, DMARC may fail even if SPF and DKIM pass.

Understanding DMARC, SPF, and DKIM

DMARC is an email authentication protocol that uses SPF and DKIM to determine whether an email is legitimate or not. SPF is a protocol that verifies the sender's IP address, while DKIM is a protocol that verifies the sender's digital signature. DMARC aligns the domain names used in the SPF and DKIM records with the domain name in the email's "From" header. If the domain names do not align, DMARC will fail, even if SPF and DKIM pass.

Handling DMARC Fails when SPF and DKIM Pass

When an email is sent from a different mail server than the one receiving it, DMARC may fail even if SPF and DKIM pass. This is because the domain names used in the SPF and DKIM records do not align with the domain name in the email's "From" header. To handle this situation, there are a few options:

• Use a different "From" domain: Use a different domain name in the email's "From" header that aligns with the domain names used in the SPF and DKIM records. This will allow DMARC to pass.
• Use a subdomain: Use a subdomain of the primary domain name in the email's "From" header. This will allow DMARC to pass as long as the subdomain is included in the SPF and DKIM records.
• Relax DMARC policy: Relax the DMARC policy to allow emails that fail DMARC to be delivered. This is not recommended as it can increase the risk of spoofing and phishing attacks.

Example Mail Server Configuration

Here is an example configuration for a mail server that sends emails from a different server: