Steven Hook wrote:

I'm sure - I've actually tried both options - the HTML option is
selected, but I don't know how to check the actual encoding of the
sent message.

Examine it in OE. While viewing the nessage in Inbox, press Ctrl-F3. This
should bring up the Message Source window. Look at the MIME headers and see
if there is a "TNEF" section and a WINMAIL.DAT attachment.
--
Brian Tillman [MVP-Outlook]