<me seperates zing and pedantic>
You're both right
Gone are the days when it would have worked. I can't even use a SMTP proxy, such is NTL's security. But you can use one provider for POP, and another for SMTP, as zing says. That said, I think there are more exotic flavours of SMTP that would allow me to authenticate from outside the network.
At the moment I use a small outfit called "Pepperfish". Never had a problem. I think it costs about £20 a year - being a while since I made my last annual payment. They're now shutting down - not financially viable to continue. Great shame. I've got about 3 weeks to make alternative arrangements.