Lots of my clients have had issues where they have been running happily for a long time on their BT Connect email accounts and now they have suddenly stopped sending or receiving email. The change has been due to BT switching over to using Office 365 which is essentially Microsoft Outlook Online.
Here are the settings you need to feed in to your email program to get it working again. These will work with Outlook, Thunderbird, Eudora, Outlook Express etc and also work with popular services such as Gmail, Yahoo and Hotmail.
Incoming Mail Settings:
Outgoing Mail Settings:
SMTP authentication applied/ticked
Authentication - password
Where prompted for the username and password, use the full email address, eg email@example.com