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The TCP/IP Guide  9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)       9  TCP/IP Key Applications and Application Protocols            9  TCP/IP File and Message Transfer Applications and Protocols (FTP, TFTP, Electronic Mail, USENET, HTTP/WWW, Gopher)                 9  TCP/IP Electronic Mail System: Concepts and Protocols (RFC 822, MIME, SMTP, POP3, IMAP)                      9  TCP/IP Electronic Mail Message Formats and Message Processing: RFC 822 and MIME                           9  TCP/IP Enhanced Electronic Mail Message Format: Multipurpose Internet Mail Extensions (MIME)

MIME Content-Type Header and Discrete Media: Types, Subtypes and Parameters 1 2 3 4 5 6 MIME Content-Transfer-Encoding Header and Encoding Methods

MIME Encapsulated Message Type

The other composite media type is the message type, which is devoted to the special purpose of encapsulating existing e-mail messages within the body of a new message, or for encapsulating other types of messages. The following are the subtypes defined in RFC 2046:

• message/rfc822: Indicates that the body contains an encapsulated e-mail itself formatted according to the RFC 822 standard. Note that this doesn't necessarily mean it is a plain text e-mail message; it could be a MIME message (though encapsulating MIME within MIME must be done carefully…)
  
  
• message/partial: Used to allow the fragmentation of larger messages into pieces that can later be reassembled. This is described in detail in RFC 2046.
  
  
• message/external-body: Indicates that the body of the message is not actually contained in the message itself; instead, a reference is provided to where the actual body is located. Sufficient information to locate the real message body must be provided. Again, this “out of body experience” is described in RFC 2046. (Sorry, couldn't resist! J)

MIME Content-Type Header and Discrete Media: Types, Subtypes and Parameters 1 2 3 4 5 6 MIME Content-Transfer-Encoding Header and Encoding Methods