IMAP UNAUTHENTICATE Extension for Connection Reuse
RFC 8437

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Internet Engineering Task Force (IETF)                         C. Newman
Request for Comments: 8437                                        Oracle
Updates: 3501                                                August 2018
Category: Standards Track
ISSN: 2070-1721

           IMAP UNAUTHENTICATE Extension for Connection Reuse

Abstract

   This specification extends the Internet Message Access Protocol
   (IMAP) to allow an administrative client to reuse the same IMAP
   connection on behalf of multiple IMAP user identities.

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
   https://www.rfc-editor.org/info/rfc8437.

Copyright Notice

   Copyright (c) 2018 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
   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.

Newman                       Standards Track                    [Page 1]
RFC 8437        IMAP UNAUTHENTICATE for Connection Reuse     August 2018

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   2
   3.  UNAUTHENTICATE Command  . . . . . . . . . . . . . . . . . . .   3
   4.  Interactions  . . . . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  Stateful Extensions . . . . . . . . . . . . . . . . . . .   4
     4.2.  Client Certificates, SASL EXTERNAL, and imaps . . . . . .   5
   5.  Revised State Machine . . . . . . . . . . . . . . . . . . . .   6
   6.  Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . .   7
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   9.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .   8
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   8
     10.2.  Informative References . . . . . . . . . . . . . . . . .   9
   Appendix A.  Design Considerations  . . . . . . . . . . . . . . .  11
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  11
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   Modern IMAP [RFC3501] server deployments often have peer systems with
   administrative privilege that perform actions on behalf of IMAP end
   users.  For example, a voicemail gateway can use IMAP to store a
   user's voicemail and mark that voicemail as \Seen when the user
   listens to it via the phone interface.  These systems can issue the
   IMAP AUTHENTICATE command with administrative credentials to act on
   behalf of other users.  However, with the IMAP base specification,
   these specialized IMAP clients must close the connection and create a
   new connection for each user.  For efficiency reasons, it is
   desirable for these clients to reuse the same connection,
   particularly if SSL has been negotiated.  This specification proposes
   the UNAUTHENTICATE command to achieve this goal.

   The IMAP state machine described in Section 3 of RFC 3501 does not
   have a transition from authenticated or selected state to not
   authenticated state.  The UNAUTHENTICATE command adds this
   transition.

2.  Conventions Used in This Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

Newman                       Standards Track                    [Page 2]
RFC 8437        IMAP UNAUTHENTICATE for Connection Reuse     August 2018

3.  UNAUTHENTICATE Command

   Arguments:  None

   Responses:  No specific response for this command

   Result:     OK - Completed, now in not authenticated state
               BAD - Command unknown or arguments invalid