This chapter is about the specific programs that compose mail -- like comp and repl. The chapter starts with a step-by-step explanation of how mail messages are created. There's also information that applies to all the mail-composition programs -- how to use mail aliases, what you can do at the What now? prompt, and so on. The Section Composing and Sending MIME Messages explains how to make MIME messages; there are other MIME tidbits spread through the chapter, too.
If you want to use a new text editor or programs like a spelling or diction checker, the Section What now? -- and the whatnow Program shows you how.
The Section MH Aliases describes a way to save time, to shorten long addresses, and to give an easy-to-remember name to a group of addresses.
MH gives you a lot of flexibility with draft messages, especially if you make a draft folder.
The chapter ends with tips about individual commands like repl -- for example, how to include the original message in your reply...and how to mail files.