Error 1003, 11

I tried sending email with a wmv attachment of 11 mb. It was scanned by Norton but at the end I got an error message 1003, 11 with a list of options I could try to resolve the problem. I tried most of them (like reducing the file size, checking whether or not the recipient could receive that size file,tried sending to myselfat one of my other email addys, turning off email outgoing scanning etc)

 

But still got the same error message (even with a smaller file size)

 

Thye one's I sent to myself eventually showed as being sent and were in my sent folder, but I did not get them.

 

Any idea what is causing this and how I can get round the problem.

 

btw the wmv attachment was a home made one and was scanned by norton prior to me trying to send it and it came up clean.