The Sieve Mail-Filtering Language -- Extensions for Checking Mailbox Status and Accessing Mailbox Metadata
RFC 5490

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Network Working Group                                        A. Melnikov
Request for Comments: 5490                                 Isode Limited
Category: Standards Track                                     March 2009

                 The Sieve Mail-Filtering Language --
Extensions for Checking Mailbox Status and Accessing Mailbox Metadata

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.

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Abstract

   This memo defines an extension to the Sieve mail filtering language
   (RFC 5228) for accessing mailbox and server annotations, checking for
   mailbox existence, and controlling mailbox creation on "fileinto"
   action.

Melnikov                    Standards Track                     [Page 1]
RFC 5490                     Sieve METADATA                   March 2009

Table of Contents

   1. Introduction ....................................................2
   2. Conventions Used in This Document ...............................2
   3. "mailbox" and "mboxmetadata" Extensions .........................2
      3.1. Test "mailboxexists" .......................................2
      3.2. ":create" Argument to "fileinto" Command ...................3
      3.3. Test "metadata" ............................................4
      3.4. Test "metadataexists" ......................................4
   4. "servermetadata" Extension ......................................5
      4.1. Test "servermetadata" ......................................5
      4.2. Test "servermetadataexists" ................................6
   5. Security Considerations .........................................6
   6. IANA Considerations .............................................7
   7. Acknowledgements ................................................7
   8. References ......................................................8
      8.1. Normative References .......................................8
      8.2. Informative References .....................................8

1.  Introduction

   This memo defines an extension to the Sieve mail filtering language
   [SIEVE] for accessing mailbox and server annotations.  This allows
   for customization of the Sieve engine behaviour based on variables
   set using [METADATA].

   This document also defines an extension for checking for mailbox
   existence and for controlling mailbox creation on "fileinto" action.

2.  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].

   Conventions for notations are as in [SIEVE] Section 1.1, including
   the use of [ABNF].

   This document is written with an assumption that readers are familiar
   with the data model and terms defined in Section 3 of [METADATA].

3.  "mailbox" and "mboxmetadata" Extensions

3.1.  Test "mailboxexists"

   Usage:  mailboxexists <mailbox-names: string-list>

Melnikov                    Standards Track                     [Page 2]
RFC 5490                     Sieve METADATA                   March 2009

   The "mailboxexists" test is true if all mailboxes listed in the
   "mailbox-names" argument exist in the mailstore, and each allows the
   user in whose context the Sieve script runs to "deliver" messages
   into it.  When the mailstore is an IMAP server, "delivery" of
   messages is possible if:

   a.  the READ-WRITE response code is present for the mailbox (see