RFC 2060 (rfc2060) - Page 2 of 82


Internet Message Access Protocol - Version 4rev1



Alternative Format: Original Text Document



RFC 2060                       IMAP4rev1                   December 1996


   Other compatibility issues with IMAP2bis, the most common variant of
   the earlier protocol, are discussed in [IMAP-COMPAT].  A full
   discussion of compatibility issues with rare (and presumed extinct)
   variants of [IMAP2] is in [IMAP-HISTORICAL]; this document is
   primarily of historical interest.

Table of Contents

IMAP4rev1 Protocol Specification ..................................    4
1.      How to Read This Document .................................    4
1.1.    Organization of This Document .............................    4
1.2.    Conventions Used in This Document .........................    4
2.      Protocol Overview .........................................    5
2.1.    Link Level ................................................    5
2.2.    Commands and Responses ....................................    6
2.2.1.  Client Protocol Sender and Server Protocol Receiver .......    6
2.2.2.  Server Protocol Sender and Client Protocol Receiver .......    7
2.3.    Message Attributes ........................................    7
2.3.1.  Message Numbers ...........................................    7
2.3.1.1.        Unique Identifier (UID) Message Attribute .........    7
2.3.1.2.        Message Sequence Number Message Attribute .........    9
2.3.2.  Flags Message Attribute ....................................   9
2.3.3.  Internal Date Message Attribute ...........................   10
2.3.4.  [RFC-822] Size Message Attribute ..........................   11
2.3.5.  Envelope Structure Message Attribute ......................   11
2.3.6.  Body Structure Message Attribute ..........................   11
2.4.    Message Texts .............................................   11
3.      State and Flow Diagram ....................................   11
3.1.    Non-Authenticated State ...................................   11
3.2.    Authenticated State .......................................   11
3.3.    Selected State ............................................   12
3.4.    Logout State ..............................................   12
4.      Data Formats ..............................................   12
4.1.    Atom ......................................................   13
4.2.    Number ....................................................   13
4.3.    String .....................................................  13
4.3.1.  8-bit and Binary Strings ..................................   13
4.4.    Parenthesized List ........................................   14
4.5.    NIL .......................................................   14
5.      Operational Considerations ................................   14
5.1.    Mailbox Naming ............................................   14
5.1.1.  Mailbox Hierarchy Naming ..................................   14
5.1.2.  Mailbox Namespace Naming Convention .......................   14
5.1.3.  Mailbox International Naming Convention ...................   15
5.2.    Mailbox Size and Message Status Updates ...................   16
5.3.    Response when no Command in Progress ......................   16
5.4.    Autologout Timer ..........................................   16
5.5.    Multiple Commands in Progress .............................   17



Crispin                     Standards Track