o/s windows 7

Incomming mail is received ok.

It only affects outgoing mail. when i try to send the error message comes up. I have deleted all outging mail that was stuck but error still continues.

Your server has unexpectedly terminated the connection. Possible causes for this include server problems, network problems, or a long period of inactivity.

Subject 'test'
Server: 'smtp.tiscali.co.uk'
Windows Live Mail Error ID: 0x800CCC0F
Protocol: SMTP
Port: 25
Secure(SSL): No
Socket Error: 10053

This is error message i get. any help would be appreciated