I would suggest you send multipart/alternative  in order that the recipient gets Text version and Html version. It sounds like he/she is using Outlook Express (or whatever it is called now). See menu Tools/Options/Outgoing Mail/Sending Mail and check "Generate Multipart..."

Martin

I've recently sent someone some plain text emails including some forwarded messages. He says that he can "see" them but can't open them.
He has no idea of what operating system he is using apart from it being Windows nor what his email client is.

Is it possible that his client has been set up to only open HTML emails and, if so, if I send them in RTF is it more likely that he will be able to open them?

Bob