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 DomainKeys Identified Mail (DKIM) 

DomainKeys Identified Mail (DKIM) lets an organization take responsibility for a message that is in transit.  The organization is a handler of the message, either as its originator or as an intermediary. Their reputation is the basis for evaluating whether to trust the message for further handling, such as delivery. Technically DKIM provides a method for validating a domain name identity that is associated with a message through cryptographic authentication. The identity is independent of other email identities, such as the author's From: field.


Signing Specification Products & Services IETF

DKIM attaches a new domain name identifier to a message and uses cryptographic techniques to validate authorization for its presence. The identifier is independent of any other identifier in the message, such in the author's From: field.

The first version of DKIM synthesized and enhanced Yahoo!'s DomanKeys and Cisco's Identified Internet Mail specifications. It was the result of a year-long collaboration among numerous industry players, during 2005, to develop an open-standard e-mail authentication specification. Participants included Alt-N Technologies, AOL, Brandenburg InternetWorking, Cisco, EarthLink, IBM, Microsoft, PGP Corporation, Sendmail, StrongMail Systems, Tumbleweed, VeriSign and Yahoo!. The team produced the initial specification and several implementations. It then submitted the work to the IETF for further enhancement and formal standardization.

The result is a set of IETF specifications and supporting documentation.

  • DKIM 3-slide Teaser, D. Crocker
      »  pdf, ppt
  • DKIM, Roman Valls Guimerà, esCERT  —
    Introduction, examples and analysis, countering the myth that DKIM is expensive
      »   pdf
    , odp


Press Contacts

A number of organizations have offered Press Contacts for matters relating to DKIM.

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The current specifications are recommended for immediate use:

  • DKIM Service Overview, RFC 5585
      »  html, pdf, txt 
  • DKIM Signatures
      »  RFC 6376
  • DomainKeys Identified Mail (DKIM) Development, Deployment and Operations, RFC 5863 
      »  html, txt
  • DKIM Author Domain Signing Practices (ADSP)
     »  RFC 5617
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See this list of Organizations Providing Software, Hardware or Services with DKIM.


See this list of Consulting Services for assisting with DKIM development or deployment and use


An operations-related mailing list is available: dkim-ops.


For general discussion with other DKIM developers, join the dkim-dev mailing list.

For quick questions to developers primarily active with OpenDKIM, there is an #dkim IRC channel at

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Related Work

  • Reporting of DKIM Verification Failures, draft-kucherawy-dkim-reporting » txt
  • Abuse Feedback Reporting Format (ARF) » home
  • Message Header Field for Indicating Message Authentication Status (Auth-Results) » txt » mailing list
  • Vouch By Reference (VBR) » home


Yahoo's DomainKeys resulted in an Intellectual Property Rights claim concerning that applies to the DKIM specification.

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