Yes, I'm interested in this one too. It happened few times to me too, but I'm using Outlook Express. I was also sending mail, but small message with big attachment (2 Mb).
The good thing is that even I've got message that mail is not sent, mail is succesfully delivered to my friend (I asked him does he want me to send him mail again, and he said that he's got that one already).
Cheers !