RFC 3501 IMAPv4 March 2003 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 1.3. Special Notes to Implementors ........................... 5 2. Protocol Overview ....................................... 6 2.1. Link Level .............................................. 6 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 ...................................... 8 2.3.1. Message Numbers ......................................... 8 2.3.1.1. Unique Identifier (UID) Message Attribute ....... 8 2.3.1.2. Message Sequence Number Message Attribute ....... 10 2.3.2. Flags Message Attribute ................................. 11 2.3.3. Internal Date Message Attribute ......................... 12 2.3.4. [RFC-2822] Size Message Attribute ....................... 12 2.3.5. Envelope Structure Message Attribute .................... 12 2.3.6. Body Structure Message Attribute ........................ 12 2.4. Message Texts ........................................... 13 3. State and Flow Diagram .................................. 13 3.1. Not Authenticated State ................................. 13 3.2. Authenticated State ..................................... 13 3.3. Selected State .......................................... 13 3.4. Logout State ............................................ 14 4. Data Formats ............................................ 16 4.1. Atom .................................................... 16 4.2. Number .................................................. 16 4.3. String .................................................. 16 4.3.1. 8-bit and Binary Strings ................................ 17 4.4. Parenthesized List ...................................... 17 4.5. NIL ..................................................... 17 5. Operational Considerations .............................. 18 5.1. Mailbox Naming .......................................... 18 5.1.1. Mailbox Hierarchy Naming ................................ 19 5.1.2. Mailbox Namespace Naming Convention ..................... 19 5.1.3. Mailbox International Naming Convention ................. 19 5.2. Mailbox Size and Message Status Updates ................. 21 5.3. Response when no Command in Progress .................... 21 5.4. Autologout Timer ........................................ 22 5.5. Multiple Commands in Progress ........................... 22 6. Client Commands ........................................ 23 6.1. Client Commands - Any State ............................ 24 6.1.1. CAPABILITY Command ..................................... 24 6.1.2. NOOP Command ........................................... 25 6.1.3. LOGOUT Command ......................................... 26 Crispin Standards Track