DomainKeys Identified Mail (DKIM) Development, Deployment, and Operations
RFC 5863

Internet Engineering Task Force (IETF)                         T. Hansen
Request for Comments: 5863                             AT&T Laboratories
Category: Informational                                        E. Siegel
ISSN: 2070-1721                                               Consultant
                                                         P. Hallam-Baker
                                             Default Deny Security, Inc.
                                                              D. Crocker
                                             Brandenburg InternetWorking
                                                                May 2010

                   DomainKeys Identified Mail (DKIM)
                Development, Deployment, and Operations

Abstract

   DomainKeys Identified Mail (DKIM) allows an organization to claim
   responsibility for transmitting a message, in a way that can be
   validated by a recipient.  The organization can be the author's, the
   originating sending site, an intermediary, or one of their agents.  A
   message can contain multiple signatures, from the same or different
   organizations involved with the message.  DKIM defines a domain-level
   digital signature authentication framework for email, using public
   key cryptography and using the domain name service as its key server
   technology.  This permits verification of a responsible organization,
   as well as the integrity of the message content.  DKIM will also
   provide a mechanism that permits potential email signers to publish
   information about their email signing practices; this will permit
   email receivers to make additional assessments about messages.
   DKIM's authentication of email identity can assist in the global
   control of "spam" and "phishing".  This document provides
   implementation, deployment, operational, and migration considerations
   for DKIM.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

Hansen, et al.                Informational                     [Page 1]
RFC 5863         DKIM Development/Deployment/Operations         May 2010

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc5863.

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Table of Contents

   1. Introduction ....................................................4
   2. Using DKIM as Part of Trust Assessment ..........................4
      2.1. A Systems View of Email Trust Assessment ...................4
      2.2. Choosing a DKIM Tag for the Assessment Identifier ..........6
      2.3. Choosing the Signing Domain Name ...........................8
      2.4. Recipient-Based Assessments ...............................10
      2.5. Filtering .................................................12
   3. DKIM Key Generation, Storage, and Management ...................15
      3.1. Private Key Management: Deployment and Ongoing