Length Considerations Different length communications need different considerations. I have one correspondent who writes and writes. Sometimes several a day. They're long, and tough to read. By the time I'm two thirds of the way through, I've forgotten the first part.
Short emails are pretty much covered in the previous section.
The important thing to remember about subheads is that they not only provide reader queues, but they help you organize your thoughts and establish important sections. Subheads can be formatted as a single head on its own line with a blank line before and after. These call special attention to the item, and with the double-dash, or 'equal' mark, you can distinguish between major heads and sub heads. With long emails, email newsletters or email press releases the rules of white space and clarity apply. Unless your readers expect an email newsletter or some other lengthy communication, they'll probably never get to the end.