The answer to spam (apart from death/prison) lies with your ISP
My ISP (M-Web/Iafrica) has heavy-duty anti-spam, worm and virus filters in action and despite the fact that I'm online a lot I get very little spam.
An external firewall, Mailwasher, AVG and an up-to-date HOSTS file deal with the few that trickle through.
My brother in London (admittedly less sophisticated in his defences) is deluged with this garbage.
Your ISP should be dealing with this - if they're not, pressure them or change to one who does.