As I recall (although I have no desire to reinstall it and check!) if you
leave your default settings at Courier 10 or whatever they bless, and you
do nothing except press the keys H,I,space,M,O,M and hit Send, it will go
as plain text. The minute you do almost anything else, it will switch to
HTML. Even if you reset all the font/graphics for a message (the standard
way to try and send plain text message by message) you will still get HTML
if you have quoted text, URL's etc. Ironically, as I think has been
pointed out already in this thread, AOL's Web mail interface allows plain
text sending much more easily.
David missed my point about Outlook Express. Of course it CAN be reliably
set to send plain text, in fact when captured in enemy territory (like an
in-law's PC :)) I am glad it's preinstalled for my temporary use that way.
However, real users in the real world tend to end up LIKING the formatted
stuff, and they use it when communicating with each other, and don't
necessarily remember to, or want to, switch in and out of "dumb text mode"
just for your list. If your list is in their address book they can specify
plain text, but if they're just replying out of a spool they may not have
preferences imposed.
In doing some side research on this question I found dozens of lists
bemoaning the AOL thing on line in various forms. You would think that
they would take the hint, but I wouldn't hold my breath.