Just to clarify matters, what happens is that the JPG attachment shows up in the body of the email as an unreasonably large picture. Yes there is an icon on the attachment line which, if clicked, will open up the attachment in whatever program has been pre-selected.
The problem is that the pictures are showing in the body of the email. I don't get this in Thunderbird, I just get the attachment icons showing.
Anyway I've asked him to try rikbean's solution and I'll report back sometime tomorrow.
Thanks for your input guys, it really is appreciated.
Ian