The Require-Recipient-Valid-Since Header Field and SMTP Service Extension
RFC 7293
Internet Engineering Task Force (IETF) W. Mills
Request for Comments: 7293 Yahoo! Inc.
Category: Standards Track M. Kucherawy
ISSN: 2070-1721 Facebook, Inc.
July 2014
The Require-Recipient-Valid-Since Header Field
and SMTP Service Extension
Abstract
This document defines an extension for the Simple Mail Transfer
Protocol (SMTP) called "RRVS" to provide a method for senders to
indicate to receivers a point in time when the ownership of the
target mailbox was known to the sender. This can be used to detect
changes of mailbox ownership and thus prevent mail from being
delivered to the wrong party. This document also defines a header
field called "Require-Recipient-Valid-Since" that can be used to
tunnel the request through servers that do not support the extension.
The intended use of these facilities is on automatically generated
messages, such as account statements or password change instructions,
that might contain sensitive information, though it may also be
useful in other applications.
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 5741.
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/rfc7293.
Mills & Kucherawy Standards Track [Page 1]
RFC 7293 Require-Recipient-Valid-Since July 2014
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Description . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. The "RRVS" SMTP Extension . . . . . . . . . . . . . . . . 5
3.2. The "Require-Recipient-Valid-Since" Header Field . . . . 5
3.3. Timestamps . . . . . . . . . . . . . . . . . . . . . . . 6
4. Use By Generators . . . . . . . . . . . . . . . . . . . . . . 6
5. Handling By Receivers . . . . . . . . . . . . . . . . . . . . 7
5.1. SMTP Extension Used . . . . . . . . . . . . . . . . . . . 7
5.1.1. Relays . . . . . . . . . . . . . . . . . . . . . . . 8
5.2. Header Field Used . . . . . . . . . . . . . . . . . . . . 9
5.2.1. Design Choices . . . . . . . . . . . . . . . . . . . 10
5.3. Clock Synchronization . . . . . . . . . . . . . . . . . . 11
6. Relaying without RRVS Support . . . . . . . . . . . . . . . . 11
6.1. Header Field Conversion . . . . . . . . . . . . . . . . . 11
7. Header Field with Multiple Recipients . . . . . . . . . . . . 12
8. Special Use Addresses . . . . . . . . . . . . . . . . . . . . 13
8.1. Mailing Lists . . . . . . . . . . . . . . . . . . . . . . 13
8.2. Single-Recipient Aliases . . . . . . . . . . . . . . . . 13
8.3. Multiple-Recipient Aliases . . . . . . . . . . . . . . . 14
8.4. Confidential Forwarding Addresses . . . . . . . . . . . . 14
8.5. Suggested Mailing List Enhancements . . . . . . . . . . . 14
9. Continuous Ownership . . . . . . . . . . . . . . . . . . . . 15
10. Digital Signatures . . . . . . . . . . . . . . . . . . . . . 15
11. Authentication-Results Definitions . . . . . . . . . . . . . 16
12. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 16
12.1. SMTP Extension Example . . . . . . . . . . . . . . . . . 17
12.2. Header Field Example . . . . . . . . . . . . . . . . . . 17
12.3. Authentication-Results Example . . . . . . . . . . . . . 17
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RFC 7293 Require-Recipient-Valid-Since July 2014
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