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Versions: 00                                                            
Network Working Group                                         R. Earhart
Internet Draft: URL-POP3                                 Carnegie Mellon
Document: draft-earhart-url-pop3-00.txt                     January 1997
Expires July 1998


                          A POP3 URL Interface

Status of this Memo

   This document is an Internet-Draft.  Internet-Drafts are working
   documents of the Internet Engineering Task Force (IETF), its areas,
   and its working groups.  Note that other groups may also distribute
   working documents as Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six
   months.  and may be updated, replaced, or obsoleted by other
   documents at any time.  It is not appropriate to use Internet-Drafts
   as reference material or to cite them other than as "work in
   progress".

   To learn the current status of any Internet-Draft, please check the
   1id-abstracts.txt listing contained in the Internet-Drafts Shadow
   Directories on ftp.is.co.za (Africa), ftp.nordu.net (Europe),
   munnari.oz.au (Pacific Rim), ds.internic.net (US East Coast), or
   ftp.isi.edu (US West Coast).

   This document suggests a proposed protocol for the Internet
   community, and requests discussion and suggestions for improvements.
   Distribution of this draft is unlimited.

   The protocol discussed in this document is experimental and subject
   to change.  Persons planning on either implementing or using this
   protocol are STRONGLY URGED to get in touch with the author before
   embarking on such a project.


Abstract

   It is occasionally useful to be able to reference a generic server to
   be used for message submission.  URLs provide a good mechanism for
   refering to arbitrary network resources.  The POP3 URL scheme allows
   a URL to specify a POP3 [POP3] server, allowing other protocols to
   use a general ''URL to be used for mail access'' in place of an
   explicit reference to POP3.






Earhart                                                         [Page 1]


Internet DRAFT            A POP3 URL Interface              January 1997


1.   Conventions Used in this Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [KEYWORDS].


2.   POP3 URL Scheme

   The POP3 URL follows the common Internet scheme syntax as defined in
   [BASIC-URL] except that plaintext passwords are not permitted.  If
   :<port> is omitted, the port defaults to 110.

   The specified server should not be assumed to have any services
   available other than POP3.  Other than authentication, no protocol
   actions are implied by an POP3 URL; a POP3 URL only specifies the
   location of a POP3 service, not what to do with it (common actions
   are to use the service to discover whether a user has pending mail,
   and to retrieve such mail).

   A POP3 URL has the following general form:

      url-pop3  = "pop3://" url-server

   "pop3" refers to the URL scheme; "://" is used to indicate a
   reference to an Internet host address.  The <url-server> element
   includes the hostname, and optional user name, authentication
   mechanism and port number.

   Note that unsafe or reserved characters such as " " or "?" MUST be
   hex encoded as described in the URL specification [BASIC-URL].  Hex
   encoded octets are interpreted according to UTF-8 [UTF8].


3.   POP3 URL User Name and Authentication Mechanism

   A user name and/or authentication mechanism may be supplied.  They
   are used to perform authentication, as per [POP3-AUTH], after making
   the connection to the POP3 server.  If no user name or authentication
   mechanism is supplied, then clients SHOULD try known authentication
   mechanisms in order of decreasing strength, as permitted by the user.
   If an authentication mechanism is supplied without a user name, then
   one SHOULD be obtained from the specified mechanism or requested from
   the user as appropriate.  If a user name is supplied without an
   authentication mechanism then ";AUTH=*" is assumed.

   The ";AUTH=" authentication parameter is interpreted as described in
   the IMAP URL Scheme [IMAP-URL].



Earhart                                                         [Page 2]


Internet DRAFT            A POP3 URL Interface              January 1997


   Note that if unsafe or reserved characters such as " " or ";" are
   present in the user name or authentication mechanism, they MUST be
   encoded as described in the URL specification [BASIC-URL].


4.   Formal Syntax

   The following syntax specification uses the augmented Backus-Naur
   Form (BNF) notation as specified in [ABNF].  This uses the ABNF core
   rules as specified in Appendix A of the ABNF specification [ABNF].

   Except as noted otherwise, all alphabetic characters are case-
   insensitive.  The use of upper or lower case characters to define
   token strings is for editorial clarity only.  Implementations MUST
   accept these strings in a case-insensitive fashion.

      url-auth           = ";AUTH=" ("*" / url-enc-auth)

      url-achar          = uchar / "&" / "=" / "~"
                           ;; See [BASIC-URL] for definition of "uchar"

      url-enc-auth       = 1*url-achar
                           ;; encoded version of auth-type-name above

      url-enc-user       = *url-achar
                           ;; encoded version of login userid

      url-pop3           = "pop3://" url-server

      url-server         = [url-enc-user [url-auth] "@"] hostport
                           ;; See [BASIC-URL] for definition of "hostport"


5.   Security Considerations

   POP3 URLs have the same security considerations as IMAP URLs [IMAP-
   URL].

   Clients SHOULD make the POP3 URL being used obvious to the user, as
   using an undesireable server may compromise the user's idea of what
   mail has been recieved.  Clients SHOULD only use reasonably strong
   AUTHorization mechanisms, to ensure the privacy and integrity of the
   user's mail while in transit.








Earhart                                                         [Page 3]


Internet DRAFT            A POP3 URL Interface              January 1997


6.   Copyright

   Copyright (C) The Internet Society 1998. All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.


7.   References

   [ABNF] Crocker, D., and Overell, P., "Augmented BNF for Syntax
   Specifications: ABNF", RFC 2234, November 1997.

      <url:ftp://ds.internic.net/rfc/rfc2234.txt>

   [BASIC-URL] Berners-Lee, T., Masinter, L., and McCahill, M., "Uniform
   Resource Locators (URL)", RFC 1738, December 1994.

      <url:ftp://ds.internic.net/rfc/rfc1738.txt>

   [IMAP-URL] Newman, C., "IMAP URL Scheme", RFC 2192, July 1997.

      <url:ftp://ds.internic.net/rfc/rfc2192.txt>







Earhart                                                         [Page 4]


Internet DRAFT            A POP3 URL Interface              January 1997


   [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
   Requirement Levels", BCP 14, RFC 2119, March 1997.

      <url:ftp://ds.internic.net/rfc/rfc2119.txt>

   [POP3] Myers, J., and Rose, M., "Post Office Protocol - Version 3.",
   STD 53, RFC 1939, May 1996.

      <url:ftp://ds.internic.net/rfc/rfc1734.txt>

   [POP3-AUTH] Myers, J., "POP3 AUTHentication command", RFC 1734,
   December 1994.

      <url:ftp://ds.internic.net/rfc/rfc1734.txt>

   [UTF8] Yergeau, F., "UTF-8, a transformation format of Unicode and
   ISO 10646", RFC 2044, October 1996.

      <url:ftp://ds.internic.net/rfc/rfc2044.txt>


8.   Author's Address

   Robert H. Earhart
   Carnegie Mellon
   5000 Forbes Ave.
   Pittsburgh PA, 15213-3890

   Email: earhart+@cmu.edu


Expires July 1998



















Earhart                                                         [Page 5]