Many members subscribe to the digest version of the list.
And finally, many users pay for access on a per-byte basis. MIME is the Multimedia Internet Mail Extensions, and is a specification that programmers use to enable mail interoperability. Of course, their emailer has to support MIME in order for them to receive your message properly. In fact, the modern popular email packages that offer MIME encoding often use HTML to format the text and use the MIME standard for attached files, etc. The recipient of your note would use a similar program to decode your text information back to binary form.