Recommended Usage of the Authenticated Received Chain (ARC)
draft-ietf-dmarc-arc-usage-02
DMARC Working Group S. Jones
Internet-Draft DMARC.org
Intended status: Informational J. Rae-Grant
Expires: December 22, 2017 Google
T. Adams
Paypal
K. Andersen, Ed.
LinkedIn
June 20, 2017
Recommended Usage of the Authenticated Received Chain (ARC)
draft-ietf-dmarc-arc-usage-02
Abstract
The Authentication Received Chain (ARC) provides a means to preserve
email authentication results and verify the identity of email message
handlers, each of which participates by inserting certain header
fields before passing the message on. But the specification does not
indicate how intermediaries and receivers should interpret or utilize
ARC. This document will provide guidance in these areas.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 22, 2017.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
Jones, et al. Expires December 22, 2017 [Page 1]
Internet-Draft ARC-USAGE June 2017
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. How does ARC work? . . . . . . . . . . . . . . . . . . . . . 3
3. Guidance for Receivers/Validators . . . . . . . . . . . . . . 4
3.1. What is the significance of an intact ARC chain? . . . . 4
3.2. What exactly is an "intact" ARC chain? . . . . . . . . . 4
3.3. What is the significance of an invalid ("broken") ARC
chain? . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.4. What does the absence of an ARC chain in a message mean? 5
3.5. What reasonable conclusions can you draw based upon
seeing lots of mail with ARC chains? . . . . . . . . . . 5
3.6. What if none of the intermediaries have been seen
previously? . . . . . . . . . . . . . . . . . . . . . . . 6
3.7. What about ARC chains where some intermediaries are known
and others are not? . . . . . . . . . . . . . . . . . . . 6
3.8. What should message handlers do when they detect
malicious content in messages where ARC is present? . . . 6
3.9. What feedback does a sender or domain owner get about ARC
when it is applied to their messages? . . . . . . . . . . 7
3.10. What prevents a malicious actor from removing the ARC
header fields, altering the content, and creating a new
ARC chain? . . . . . . . . . . . . . . . . . . . . . . . 7
4. Guidance for Intermediaries . . . . . . . . . . . . . . . . . 8
4.1. What is an Intermediary under ARC? . . . . . . . . . . . 8
4.2. What are the minimum requirements for an ARC
Intermediary? . . . . . . . . . . . . . . . . . . . . . . 8
4.2.1. More specifically a participating ARC intermediary
must do the following: . . . . . . . . . . . . . . . 8
4.3. Should every MTA be an ARC participant? . . . . . . . . . 8
4.4. What should an intermediary do in the case of an invalid
Show full document text