no idea what could be wrong, sorry - it could be your friends smtp server that is the problem, rather than NTL ?
Couple of things to try - set up another mailbox & see if you get the same problem with a different addy, or set up forwarding to an external account, such as hotmail, or gmail - and see if the problem still occurs
http://www.ntlworld.com/help/your_ac...ail_manage.php
is the place to go to set it up