A guess is that people are sending HTML formatted messages to the list and
either the list server, a mail server somewhere in between, or individual's
e-mail clients are not able to recognize and display HTML. So you see the
HTML code instead of the prettied-up text that the HTML is supposed to
render.
I use Outlook Express and I know that it defaults to HTML-formatted
messages. Even when you set the default to "Plain Text" sometimes when
*replying* it still wants to run home to mama and format in HTML--you must
manually set it to "Plain Text" on a message-by-message basis. (Unless
there is some hidden setting I have not found.)
So. . . if no server-related setting can be fiddled-with, I recommend folks
take special care to ensure they are sending "Plain Text" messages to the
list and see if that helps.
Just my $.02.
(I am sending this as "Plain Text." Hope you can read it!)
-Michael