Sending MMS picture messages on O2 with a T720i

Has anybody ever managed to do this ? Please post here if you have.

I have all my settings correct, and can send an MMS with a picture attached
to my own account. The message sends OK.

The message arrives within a few minutes, but when I try to open it, the
picture does not show - just a little icon indicating that there is a
picture attached to the message. The phone flashes up a message saying
"Uanble to open file" and then goes back to the message menu.

I have heard a lot from people having trouble sending picture messages using
a T720 on O2, but have never yet heard of anyone who has managed it.

Searching the O2 web site brings up loads of stuff on settings for different
phones to use MMS, but worryingly, I can find no phone specific settings for
the Motorola T720i. Do O2 even support the Motorola ?

Lofty