Post Office Protocol Version 3 (POP3) Support for UTF-8
RFC 6856

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Internet Engineering Task Force (IETF)                        R. Gellens
Request for Comments: 6856                         QUALCOMM Incorporated
Obsoletes: 5721                                                C. Newman
Category: Standards Track                                         Oracle
ISSN: 2070-1721                                                   J. Yao
                                                                   CNNIC
                                                             K. Fujiwara
                                                                    JPRS
                                                              March 2013

        Post Office Protocol Version 3 (POP3) Support for UTF-8

Abstract

   This specification extends the Post Office Protocol version 3 (POP3)
   to support international strings encoded in UTF-8 in usernames,
   passwords, mail addresses, message headers, and protocol-level text
   strings.

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/rfc6856.

Gellens, et al.              Standards Track                    [Page 1]
RFC 6856                 POP3 Support for UTF-8               March 2013

Copyright Notice

   Copyright (c) 2013 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
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   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.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Conventions Used in This Document  . . . . . . . . . . . .  3
   2.  "UTF8" Capability  . . . . . . . . . . . . . . . . . . . . . .  4
     2.1.  The "UTF8" Command . . . . . . . . . . . . . . . . . . . .  5
     2.2.  USER Argument to "UTF8" Capability . . . . . . . . . . . .  6
   3.  "LANG" Capability  . . . . . . . . . . . . . . . . . . . . . .  7
     3.1.  Definition . . . . . . . . . . . . . . . . . . . . . . . .  7
     3.2.  Discussion . . . . . . . . . . . . . . . . . . . . . . . .  7
     3.3.  Examples . . . . . . . . . . . . . . . . . . . . . . . . .  8
   4.  Non-ASCII Character Maildrops  . . . . . . . . . . . . . . . .  9
   5.  "UTF8" Response Code . . . . . . . . . . . . . . . . . . . . . 10
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 11
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 12
   Appendix A.  Design Rationale  . . . . . . . . . . . . . . . . . . 13
   Appendix B.  Acknowledgments . . . . . . . . . . . . . . . . . . . 13

Gellens, et al.              Standards Track                    [Page 2]
RFC 6856                 POP3 Support for UTF-8               March 2013

1.  Introduction

   This document forms part of the Email Address Internationalization
   protocols described in the Email Address Internationalization
   Framework document [RFC6530].  As part of the overall Email Address
   Internationalization work, email messages can be transmitted and
   delivered containing a Unicode string encoded in UTF-8 in the header
   and/or body, and maildrops that are accessed using POP3 [RFC1939]