2.1.3.3 Body Text

When generating a pure MIME message, MIME writers generate a single MIME entity for the message body, and it MUST be the first entity generated. (For Message objects without attachments, it SHOULD be the only MIME entity generated.) The MIME entity generated for the message body can have several different structures, some of them fairly complex.

For diagrams of the message structure with attachments, and for details about how to determine whether an Attachment object represents an inline attached file, see section 2.1.3.4.