RFC5322 specifies the Internet Message Format (IMF), a syntax for text messages that are sent between computer users, within the framework of "electronic mail" messages.
RFC5322 is a revision of RFC2822, which itself superseded RFC822 ("Standard for the Format of ARPA Internet Text Messages". RFC5322 updates the Internet Message Format (IMF) to reflect current practice and incorporating incremental changes that were specified in other RFC's.
Multimedia Content
RFC5322 only specifies the syntax for textual messages. It makes no provision for the transmission of images, audio, or other sorts of structure data in electronic mail messages. There are several extensions published, such as the Multipurpose Internet Mail Extensions (MIME), which specifies multimedia inclusion in electronic mail messages. These provisions are outlined in RFC2045, RFC2046, and RFC2049.
Electronic Mail Envelopes
Electronic mail messages are composed of two parts, the envelope and the content. The IMF only addresses the content portion of the electronic mail message. For more information on the envelope, refer to RFC5321.
