Many of the content types that MIME supports are normally represented as binary or 8-bit character data. So this header field indicates what type of transformation was required to put the contents of message body in this format. Receiving and sending MIME messages involves being able to encode and decode them. A couple of the more common independent programs are mpack , munpack , and Metamail . Metamail is a package of utilities for handling MIME messages.
Many email programs use metamail .
The pine mailer has the native ability to handle MIME messages. For further optional information on MIME see RFC 1521 and RFC 1522 .