I have recently had problems with my various POP3 accounts and my Orange account in outlook. I was tearing my hair out all one evening.
As Richard has mentioned I had to reset my SMTP server to orangehome.co.uk following an error message from outlook.
Initially this worked OK with my normal 'Orange' email address(actually an old freeserve account), but I could not get my POP3 accounts to work. ie my email@example.com
I called the Orange help line and explained the situation.
The guy on the other end of the line was very helpful, and ran through the process with me. We did exactly what I'd already tried, and it didn't work.
He left me on hold whilst he asked somebody else. When he came back we started again and it worked following something he did.
I was so happy it worked I didn't ask what he'd done, and just presumed he'd activated a priviledge or something on my account.