Please clarify the problem. Your first sentence seems to contradict the third one.

Sorry, yes. That should be:

Why can't I send outgoing email on my BT Premium email account from within Thunderbird, when the Norton VPN is off? I get a timed out or policy block message. Somewhat perversely, it works when the VPN connection is on, although you warn that VPN connections may be rejected.

That is more coherent and more accurate. I have been chasing this for a while, so I may written the same thing multiple times, and then not noticed, when it was incomplete.