My Email isnt sending emails!

Hello,

I use windows live mail to access my email through my windows 8 laptop. 

My email address is ************@tiscali.co.uk  which is part of talktalk

I have no problem receiving emails what so ever but it is when I go to send them that an error message appears.

It is nothing to do with the email address I am sending to or my internet connection. 

Please help me!

Thank You,

Tim Holt