The Domain-based Message Authentication, Reporting & Conformance (dmarc) WG in the Applications and Real-Time Area of the IETF has been rechartered. For additional information, please contact the Area Directors or the WG Chairs. Domain-based Message Authentication, Reporting & Conformance (dmarc) ----------------------------------------------------------------------- Current status: Active WG Chairs: Barry Leiba <barryleiba@computer.org> Ned Freed <ned+dmarc@mrochek.com> Tim Draegen <tim@eudaemon.net> Assigned Area Director: Alexey Melnikov <aamelnikov@fastmail.fm> Applications and Real-Time Area Directors: Adam Roach <adam@nostrum.com> Ben Campbell <ben@nostrum.com> Alexey Melnikov <aamelnikov@fastmail.fm> Mailing list: Address: dmarc@ietf.org To subscribe: https://www.ietf.org/mailman/listinfo/dmarc Archive: https://mailarchive.ietf.org/arch/browse/dmarc/ Group page: https://datatracker.ietf.org/group/dmarc/ Charter: https://datatracker.ietf.org/doc/charter-ietf-dmarc/ Domain-based Message Authentication, Reporting & Conformance (DMARC) uses existing mail authentication technologies (SPF and DKIM) to extend validation to the RFC5322.From field. DMARC uses DNS records to add policy-related requests for receivers and defines a feedback mechanism from receivers back to domain owners. This allows a domain owner to advertise that mail can safely receive differential handling, such as rejection, when the use of the domain name in the From field is not authenticated. Existing deployment of DMARC has demonstrated utility at internet scale, in dealing with significant email abuse, and has permitted simplifying some mail handling processes. However, DMARC is problematic for mail that does not flow from operators having a relationship with the domain owner, directly to receivers operating the destination mailbox (for example, mailing lists, publish-to-friend functionality, mailbox forwarding via ".forward", and third-party services that send on behalf of clients). The working group will explore possible updates and extensions to the specifications in order to address limitations and/or add capabilities. It will also provide technical implementation guidance and review possible enhancements elsewhere in the mail handling sequence that could improve DMARC compatibility. The existing DMARC base specification is published as Informational RFC 7489 in the Independent Stream. Specifications produced by the working group will ensure preservation of DMARC utility for detecting unauthorized use of domain names, while improving the identification of legitimate sources that do not currently conform to DMARC requirements. Issues based on operational experience and/or data aggregated from multiple sources will be given priority. The working group will seek to preserve interoperability with the installed base of DMARC systems, and provide detailed justification for any non-interoperability. As the working group develops solutions to deal with indirect mail flows, it will seek to maintain the end-to-end nature of existing identifier fields in mail, in particular avoiding solutions that require rewriting of originator fields. Working group activities will pursue four tracks: 1. Addressing the issues with indirect mail flows The working group will specify mechanisms for reducing or eliminating the DMARC's effects on indirect mail flows, including deployed behaviors of many different intermediaries, such as mailing list managers, automated mailbox forwarding services, and MTAs that perform enhanced message handling that results in message modification. Among the choices for addressing these issues are: - A form of DKIM signature that is better able to survive transit through intermediaries. - Collaborative or passive transitive mechanisms that enable an intermediary to participate in the trust sequence, propagating authentication directly or reporting its results. - Message modification by an intermediary, to avoid authentication failures, such as by using specified conventions for changing the aligned identity. Consideration also will be given to survivable authentication through sequences of multiple intermediaries. 2. Reviewing and improving the base DMARC specification The working group will not develop additional mail authentication technologies, but may document desirable uses of existing authentication technologies. The base specification relies on the ability of an email receiver to determine the organizational domain responsible for sending mail. An organizational domain is the 'base' name that is allocated from a public registry; examples of registries include ".com" or ".co.uk". While the common practice is to use a "public suffix" list to determine organizational domain, it is widely recognized that this solution will not scale, and that the current list often is inaccurate. The task of defining a standard mechanism for identifying organizational domain is out of scope for this working group. However the working group can consider extending the base DMARC specification to accommodate such a standard, should it be developed during the life of this working group. Improvements in DMARC features (identifier alignment, reporting, policy preferences) will be considered, such as: - Enumeration of data elements required in "Failure" reports (specifically to address privacy issues) - Handling potential reporting abuse - Aggregate reporting to support additional reporting scenarios - Alternate reporting channels - Utility of arbitrary identifier alignment - Utility of a formalized policy exception mechanism 3. DMARC Usage The working group will document operational practices in terms of configuration, installation, monitoring, diagnosis and reporting. It will catalog currently prevailing guidelines as well as developing advice on practices that are not yet well-established but which are believed to be appropriate. The group will consider separating configuration and other deployment information that needs to be in the base spec, from information that should be in a separate guide. Among the topics anticipated to be included in the document are: - Identifier alignment configuration options - Implementation decisions regarding "pct" - Determining effective RUA sending frequency - Leveraging policy caching - Various options for integrating within an existing flow - Defining a useful, common set of options for the addresses to which feedback reports are to be sent - When and how to use local policy override options 4. Related work Extensions to SPF/DKIM/DMARC that do not already fit under the charter of any existing working group can be considered for adoption by DMARC Working Group after consultation with the responsible AD. A prime example is draft-levine-appsarea-eaiauth, which provides EAI-related updates to DMARC and the protocols upon which it depends. Any such work needs to carefully consider interoperability implications. Work Items ---------- Phase I: Draft description of interoperability issues for indirect mail flows and plausible methods for reducing them. This is now complete and published as RFC 7960. Phase II: Specification of DMARC improvements to support indirect mail flows; this is now complete as draft-ietf-dmarc-arc-protocol (ARC). Draft Guide on DMARC Usage. Phase III: Review and refinement of the DMARC specification. Completion of Guide on DMARC and ARC Usage. References ---------- DMARC - http://dmarc.org SPF - RFC7208 Authentication-Results Header Field - RFC7001 DKIM - RFC6376 Internet Message Format - RFC5322 OAR / Original Authentication Results - draft-kucherawy-original-authres Using DMARC - draft-crocker-dmarc-bcp-03 Delegating DKIM Signing Authority - draft-kucherawy-dkim-delegate-00 DKIM Third-Party Authorization Label - draft-otis-dkim-tpa-label-03 Milestones: Done - Complete Authenticated Received Chain (ARC) protocol spec Jan 2019 - Complete EAI update to SPF/DKIM/DMARC Feb 2019 - Complete Authenticated Received Chain (ARC) usage recommendations
