RFC 2221 (rfc2221) - Page 1 of 5

IMAP4 Login Referrals

Network Working Group                                           M. Gahrns
Request for Comments: 2221                                      Microsoft
Category: Standards Track                                    October 1997


                         IMAP4 Login Referrals

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1997).  All Rights Reserved.

1. Abstract

   When dealing with large amounts of users and many IMAP4 [RFC-2060]
   servers, it is often necessary to move users from one IMAP4 server to
   another.  For example, hardware failures or organizational changes
   may dictate such a move.

   Login referrals allow clients to transparently connect to an
   alternate IMAP4 server, if their home IMAP4 server has changed.

   A referral mechanism can provide efficiencies over the alternative
   'proxy method', in which the local IMAP4 server contacts the remote
   server on behalf of the client, and then transfers the data from the
   remote server to itself, and then on to the client.  The referral
   mechanism's direct client connection to the remote server is often a
   more efficient use of bandwidth, and does not require the local
   server to impersonate the client when authenticating to the remote
   server.

2. Conventions used in this document

   In examples, "C:" and "S:" indicate lines sent by the client and
   server respectively.

   A home server, is an IMAP4 server that contains the user's inbox.

   A remote server is a server that contains remote mailboxes.





Gahrns                      Standards Track