Hello Rich and welcome to the forums
I'm right in the middle of my A-levels at the moment, so I won't be able to reply very fast. Hopefully one of my friends here will come and help out as well, but for now, you've got me. I finish on Friday though, so if we don't have this resolved by then, I'll be able to commit more time to this.
Is there a website where you can access your email account online? I'm not familiar with TalkTalk, but I've got one for btconnect. If so, I would like you to log into this, then send yourself an email. Then open your Windows Mail and see if the email arrives. What I'm trying to do here is see if the problem lies with the TalkTalk server or not
Edit: Rich (richc46) to the rescue!