IMAP4 Namespace (RFC2342)
Original Publication Date: 1998-May-01
Included in the Prior Art Database: 2000-Sep-13
Internet Society Requests For Comment (RFCs)
M. Gahrns: AUTHOR [+2]
IMAP4 [RFC-2060] does not define a default server namespace. As a result, two common namespace models have evolved:
Network Working Group M. Gahrns
Request for Comments: 2342 Microsoft
Category: Standards Track C. Newman
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 (C) The Internet Society (1998). All Rights Reserved.
IMAP4 [RFC-2060] does not define a default server namespace. As a
result, two common namespace models have evolved:
The "Personal Mailbox" model, in which the default namespace that is
presented consists of only the user's personal mailboxes. To access
shared mailboxes, the user must use an escape mechanism to reach
The "Complete Hierarchy" model, in which the default namespace that
is presented includes the user's personal mailboxes along with any
other mailboxes they have access to.
These two models, create difficulties for certain client operations.
This document defines a NAMESPACE command that allows a client to
discover the prefixes of namespaces used by a server for personal
mailboxes, other users' mailboxes, and shared mailboxes. This allows
a client to avoid much of the manual user configuration that is now
necessary when mixing and matching IMAP4 clients and servers.
2. Conventions used in this document
In examples, "C:" and "S:" indicate lines sent by the client and
server respectively. If such lines are wrapped without a new "C:" or
"S:" label, then the wrapping is for editorial clarity and is not
part of the command.
Personal Namespace: A namespace that the server considers within the
personal scope of the authenticated user on a particular connection.
Typically, only the authenticated user has access to mailboxes in
their Personal Namespace. It is the part of the namespace that
belongs to the user that is allocated for mailboxes. If an INBOX
exists for a user, it MUST appear within the user's personal
namespace. In the typical case, there SHOULD be only one Personal
Namespace on a server.
Other Users' Namespace: A namespace that consists of mailboxes from
the Personal Namespaces of other users. To access mailboxes in the
Other Users' Namespace, the currently authenticated user MUST be
explicitly granted access rights. For example, it is common for a
manager to grant to their secretary access rights to their mailbox.
In the typical case, there SHOULD be only one Other Users' Namespace
on a server.