Gmail for programmers
Kaiten Mail lets you send emails in these formats:


Plain text (images and formatting will be removed)
HTML (images and formatting are preserved)
Automatic (plain text unless replying to an HTML message)


I'm not sure about the the width though. I haven't seen any setting where I can set it to 80 (or any other value).

By the way, I sync my GMail and Yahoo mail with Kaiten.