So your suggestion is that Gmail is better than BT?
Not much of an answer though, I'd still like to know under what circumstances, BT has programmed their email to display that error message so I can avoid it. If there was a secondary message stating, 'are you sure you want to continue to send this message..."? That would be just dandy... (Kinda like when you hit the delete button, you usually get another message asking, 'are you sure'?)