RFC 1521 (rfc1521) - Page 2 of 81
MIME (Multipurpose Internet Mail Extensions) Part One: Mechanisms for Specifying and Describing the Format of Internet Message Bodies
Alternative Format: Original Text Document
RFC 1521 MIME September 1993
Table of Contents
1. Introduction....................................... 3
2. Notations, Conventions, and Generic BNF Grammar.... 6
3. The MIME-Version Header Field...................... 7
4. The Content-Type Header Field...................... 9
5. The Content-Transfer-Encoding Header Field......... 13
5.1. Quoted-Printable Content-Transfer-Encoding......... 18
5.2. Base64 Content-Transfer-Encoding................... 21
6. Additional Content-Header Fields................... 23
6.1. Optional Content-ID Header Field................... 23
6.2. Optional Content-Description Header Field.......... 24
7. The Predefined Content-Type Values................. 24
7.1. The Text Content-Type.............................. 24
7.1.1. The charset parameter.............................. 25
7.1.2. The Text/plain subtype............................. 28
7.2. The Multipart Content-Type......................... 28
7.2.1. Multipart: The common syntax...................... 29
7.2.2. The Multipart/mixed (primary) subtype.............. 34
7.2.3. The Multipart/alternative subtype.................. 34
7.2.4. The Multipart/digest subtype....................... 36
7.2.5. The Multipart/parallel subtype..................... 37
7.2.6. Other Multipart subtypes........................... 37
7.3. The Message Content-Type........................... 38
7.3.1. The Message/rfc822 (primary) subtype............... 38
7.3.2. The Message/Partial subtype........................ 39
7.3.3. The Message/External-Body subtype.................. 42
7.3.3.1. The "ftp" and "tftp" access-types............... 44
7.3.3.2. The "anon-ftp" access-type...................... 45
7.3.3.3. The "local-file" and "afs" access-types......... 45
7.3.3.4. The "mail-server" access-type................... 45
7.3.3.5. Examples and Further Explanations............... 46
7.4. The Application Content-Type....................... 49
7.4.1. The Application/Octet-Stream (primary) subtype..... 50
7.4.2. The Application/PostScript subtype................. 50
7.4.3. Other Application subtypes......................... 53
7.5. The Image Content-Type............................. 53
7.6. The Audio Content-Type............................. 54
7.7. The Video Content-Type............................. 54
7.8. Experimental Content-Type Values................... 54
8. Summary............................................ 56
9. Security Considerations............................ 56
10. Authors' Addresses................................. 57
11. Acknowledgements................................... 58
Appendix A -- Minimal MIME-Conformance.................... 60
Appendix B -- General Guidelines For Sending Email Data... 63
Appendix C -- A Complex Multipart Example................. 66
Appendix D -- Collected Grammar........................... 68
Borenstein & Freed