Receivers Guidance for Implementing Branded Indicators for Message Identification (BIMI)
draft-brotman-ietf-bimi-guidance-02

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Network Working Group                                         A. Brotman
Internet-Draft                                                   Comcast
Intended status: Best Current Practice                           T. Zink
Expires: January 31, 2021                      Zink Magical Contraptions
                                                             M. Bradshaw
                                                                Fastmail
                                                           July 30, 2020

   Receivers Guidance for Implementing Branded Indicators for Message
                         Identification (BIMI)
                  draft-brotman-ietf-bimi-guidance-02

Abstract

   This document is meant to assist receivers or other mailbox providers
   by providing guidance to implementing Brand Indicators for Message
   Identification (BIMI).  This document is a companion to the main BIMI
   drafts which should first be consulted and reviewed.

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
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 31, 2021.

Copyright Notice

   Copyright (c) 2020 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
   (https://trustee.ietf.org/license-info) in effect on the date of
   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

Brotman, et al.         Expires January 31, 2021                [Page 1]
Internet-Draft                   BIMI-RG                       July 2020

   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  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Goals for BIMI  . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Should your site implement BIMI?  . . . . . . . . . . . . . .   3
   4.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Site implementations  . . . . . . . . . . . . . . . . . . . .   4
   6.  Validation of a BIMI message  . . . . . . . . . . . . . . . .   5
     6.1.  BIMI Site Requirements  . . . . . . . . . . . . . . . . .   5
     6.2.  Verified Mark Certificate (VMC) Validation  . . . . . . .   6
   7.  Communicating BIMI results between the MTA and the MUA  . . .   6
     7.1.  Image Retrieval . . . . . . . . . . . . . . . . . . . . .   6
     7.2.  TTL of cached images  . . . . . . . . . . . . . . . . . .   7
     7.3.  Image Display . . . . . . . . . . . . . . . . . . . . . .   7
     7.4.  Privacy Concerns  . . . . . . . . . . . . . . . . . . . .   7
     7.5.  Basic flow example  . . . . . . . . . . . . . . . . . . .   8
     7.6.  Message Classification  . . . . . . . . . . . . . . . . .   9
   8.  Domain Reputation . . . . . . . . . . . . . . . . . . . . . .   9
     8.1.  Rolling up based upon domain vs organizational domain . .   9
     8.2.  VMC Root of Trust . . . . . . . . . . . . . . . . . . . .  10
   9.  BIMI Playbook Checklist . . . . . . . . . . . . . . . . . . .  10
   10. Public documentation  . . . . . . . . . . . . . . . . . . . .  11
     10.1.  Documentation For Brands:  . . . . . . . . . . . . . . .  11
     10.2.  Documentation For Users: . . . . . . . . . . . . . . . .  11
   11. Appendix  . . . . . . . . . . . . . . . . . . . . . . . . . .  12
     11.1.  Glossary . . . . . . . . . . . . . . . . . . . . . . . .  12
   12. Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  13
   13. References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
   14. References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     14.1.  Normative References . . . . . . . . . . . . . . . . . .  13
     14.2.  URIs . . . . . . . . . . . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   The Brand Indicators for Message Identification (BIMI) specification
   introduces a method by which Mail User Agent (MUA, e.g., an email
   client) providers combine DMARC-based message authentication with