DKIM

The Domain Keys Identified Mail (DKIM) Internet standard enables email senders to digitally sign their messages so that receivers can verify that those messages have not been forged. The DKIM sender authentication scheme allows the recipient of a message to confirm a message originated with the sender's domain and that the message content has not been altered. A cryptography-based solution, DKIM provides businesses an industry-standard method for mitigating email fraud and protecting an organization's brand and reputation at a relatively low implementation cost. Learn more about DKIM.

DKIM has been approved by the IETF as a draft standard (RFC 4871). The protocol was developed through the cooperation of Sendmail, Cisco Systems and Yahoo!. Sendmail Founder Eric Allman served as the editor of the base standard, and Sendmail employee and .org contributor Murray Kucherawy developed the first open source implementation of DKIM. Read Eric Allman's technical overview.

With the completion of interoperability testing and the release of DKIM 2.4 sendmail.org recommends that DKIM be installed with all Internet-facing sendmail and Postfix MTAs. The widespread deployment of DKIM is an essential step to bringing phishing, fraud and even spam under control in an environment of email accountability.

More information is also available at dkim.org.

DKIM-MILTER

Sendmail, Inc. has released a free, Open Source implementation of the DKIM signing and verifying software. A portable library is also available to allow DKIM to be embedded into any application. Also provided is a "milter" (mail filter) plugin for Open Source sendmail and Open Source Postfix. The milter plugin allows system administrators to easily sign and verify messages using DKIM signatures. The DKIM-milter is supported by:

Download the DKIM-milter.

To contribute to the DKIM project, go to the SourceForge project page.

DKIM Tools

Sendmail has developed a set of tools to make it easier to configure and test DKIM installations. See the DKIM tools.

DKIM Survey

Because Sendmail believes that widespread adoption of the new DKIM protocol is critically important to the future of email, we have implemented a set of surveys to track the deployment of DKIM in key Internet segments. See the current DKIM Internet Survey.