What you're seeing should always read "Multipart/Mixed" rather tham "Multipart/Related" - See RFC 2387. I have a suspicion that these messages may be being sent via webmail.
Whatever it is, it's the originating end that's at fault.

Edited by Deadbeat (Tue 31-Jul-12 11:29:53)

Yes, that solves it!

I've never seen "Multipart/Related" before.

Mainly utilised by MS Exchange and some webmail systems I believe but could be added anywhere along the journey. IIRC, there was/is a tool available to trace back through to where the problem lies.

Thanks guys.

It begs the Q as to why Mail can't handle it, particularly if it is RFC'd in 1998.

Edited by XRaySpeX (Tue 31-Jul-12 21:42:36)

The client is only doing as it's told and storing the files as attachments. It's the originator that's misconfigured and telling the client how to display the content.

But is it?

Yes, it sees the files as attachments but I can't see the diff between a .JPG within a "Multipart/Related" and one within "Multipart/Mixed", when the client displays the .JPG embedded in the body text as well in the latter case but not the former.