An anti-spam protocol from the Domain Assurance Council (DAC) that enables third party certification providers to vouch for the legitimacy of the sender's domain name in an email message. A Vouch By Reference (VBR) email message includes the name of a trusted certification provider that the recipient queries for verification. The email message is also signed via DomainKeys Identified Mail (DKIM) to verify that it has not been modified, and the signature is included in the email header. See email authentication
A Vouch By Reference email includes a VBR-Info header that contains fields for sender's domain name, type of email message and the names of one or more certification providers. For more information, visit www.domain-assurance.org.