isr.co.ro : glossary Multipart In connection with e-mail messages using the MIME (Multipurpose Internet Mail Extensions) standard, a message-format description indicating that the contents represent several different objects, possibly of different types themselves. So far, it seems, most MIME messages are multipart so that they can include both a non-text file, which needs MIME encoding before it can be sent over Internet mail, and a text file explanation.