RFC 2193 (rfc2193) - Page 1 of 9

IMAP4 Mailbox Referrals

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Network Working Group                                        M. Gahrns
Request for Comments: 2193                                   Microsoft
Category: Standards Track                               September 1997


                        IMAP4 Mailbox 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.

1. Abstract

   When dealing with large amounts of users, messages and geographically
   dispersed IMAP4 [RFC-2060] servers, it is often desirable to
   distribute messages amongst different servers within an organization.
   For example an administrator may choose to store user's personal
   mailboxes on a local IMAP4 server, while storing shared mailboxes
   remotely on another server.  This type of configuration is common
   when it is uneconomical to store all data centrally due to limited
   bandwidth or disk resources.

   Mailbox referrals allow clients to seamlessly access mailboxes that
   are distributed across several IMAP4 servers.

   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 mailbox is a mailbox that is not hosted on the user's home
   server.




Gahrns                      Standards Track
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