RFC 2045 (rfc2045) - Page 2 of 31

Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies

RFC 2045                Internet Message Bodies            November 1996


   Internet mail header fields. The fourth document, RFC 2048, specifies
   various IANA registration procedures for MIME-related facilities. The
   fifth and final document, RFC 2049, describes MIME conformance
   criteria as well as providing some illustrative examples of MIME
   message formats, acknowledgements, and the bibliography.

   These documents are revisions of RFCs 1521, 1522, and 1590, which
   themselves were revisions of RFCs 1341 and 1342.  An appendix in RFC
   2049 describes differences and changes from previous versions.

Table of Contents

   1. Introduction .........................................    3
   2. Definitions, Conventions, and Generic BNF Grammar ....    5
   2.1 CRLF ................................................    5
   2.2 Character Set .......................................    6
   2.3 Message .............................................    6
   2.4 Entity ..............................................    6
   2.5 Body Part ...........................................    7
   2.6 Body ................................................    7
   2.7 7bit Data ...........................................    7
   2.8 8bit Data ...........................................    7
   2.9 Binary Data .........................................    7
   2.10 Lines ..............................................    7
   3. MIME Header Fields ...................................    8
   4. MIME-Version Header Field ............................    8
   5. Content-Type Header Field ............................   10
   5.1 Syntax of the Content-Type Header Field .............   12
   5.2 Content-Type Defaults ...............................   14
   6. Content-Transfer-Encoding Header Field ...............   14
   6.1 Content-Transfer-Encoding Syntax ....................   14
   6.2 Content-Transfer-Encodings Semantics ................   15
   6.3 New Content-Transfer-Encodings ......................   16
   6.4 Interpretation and Use ..............................   16
   6.5 Translating Encodings ...............................   18
   6.6 Canonical Encoding Model ............................   19
   6.7 Quoted-Printable Content-Transfer-Encoding ..........   19
   6.8 Base64 Content-Transfer-Encoding ....................   24
   7. Content-ID Header Field ..............................   26
   8. Content-Description Header Field .....................   27
   9. Additional MIME Header Fields ........................   27
   10. Summary .............................................   27
   11. Security Considerations .............................   27
   12. Authors' Addresses ..................................   28
   A. Collected Grammar ....................................   29






Freed & Borenstein          Standards Track