Signaling One-Click Functionality for List Email Headers
RFC 8058

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Internet Engineering Task Force (IETF)                         J. Levine
Request for Comments: 8058                          Taughannock Networks
Category: Standards Track                                     T. Herkula
ISSN: 2070-1721                                              optivo GmbH
                                                            January 2017

        Signaling One-Click Functionality for List Email Headers

Abstract

   This document describes a method for signaling a one-click function
   for the List-Unsubscribe email header field.  The need for this
   arises out of the actuality that mail software sometimes fetches URLs
   in mail header fields, and thereby accidentally triggers
   unsubscriptions in the case of the List-Unsubscribe header field.

Status of This Memo

   This is an Internet Standards Track document.

   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).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   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/rfc8058.

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
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Levine & Herkula             Standards Track                    [Page 1]
RFC 8058                  One-Click Unsubscribe             January 2017

Table of Contents

   1.  Introduction and Motivation . . . . . . . . . . . . . . . . .   2
   2.  Definitions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Implementation  . . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  Mail Senders  . . . . . . . . . . . . . . . . . . . . . .   4
     3.2.  Mail Receivers  . . . . . . . . . . . . . . . . . . . . .   5
   4.  Additional Requirements . . . . . . . . . . . . . . . . . . .   5
   5.  Header Syntax . . . . . . . . . . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   8.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .   7
     8.1.  Simple  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     8.2.  Complex . . . . . . . . . . . . . . . . . . . . . . . . .   7
     8.3.  Complex with 'multipart/form-data'  . . . . . . . . . . .   7
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction and Motivation

   A List-Unsubscribe email header field [RFC2369] can contain HTTPS
   [RFC7230] URIs.  In that header field, the HTTPS URI is intended to
   unsubscribe the recipient of the message from the list.  But anti-
   spam software often fetches all resources in mail header fields
   automatically, without any action by the user, and there is no
   mechanical way for a sender to tell whether a request was made
   automatically by anti-spam software or manually requested by a user.
   To prevent accidental unsubscriptions, senders return landing pages
   with a confirmation step to finish the unsubscribe request.  A live
   user would recognize and act on this confirmation step, but an
   automated system would not.  That makes the unsubscription process
   more complex than a single click.

   Operators of broadcast marketing lists tend to be primarily concerned
   about deliverability of their mail: whether the mail is delivered to
   the recipients and how the messages are presented, e.g., whether in
   the primary inbox or in a junk folder.  Many mail systems allow
   recipients to report mail as spam or junk, and mail streams from
   senders whose mail is often reported as junk tend to have poor
   deliverability.  Hence, the mailers want to make it as easy as
   possible for recipients to unsubscribe; if an unsubscription process
   is too difficult, the recipient's alternative is to report mail from
   the sender as junk until the mail no longer appears in the
   recipient's inbox.

   Operators of recipient mail systems are aware that their users do not
   make a clear distinction between unsubscription and junk.  In some