Remember when in magazines they have/had cards for you to fill in for more information? What this did was put you on many junk mail mailing lists. Now whenever you visit a site a spyware goes through your pc and finds out your email address and poof, you're toast.
Another bad thing to do is to sign up for any promo mailings, even from reputable sites. The reputable site may not offer your email address to anyone but once listed, you're listed.
I use McAfee spamkiller which has an option to send an error message to the spammers supposedly then your email will eventually be removed as being non valid, yeah as if.
Supposedly in the US, the US congress is trying to pass a bill that will make it illegal to spam anyone. If memory serves the international court is/was involved in a fight to stop spamming as it is overwelming servers with the shear volume of crap being sent out.
Crazy as it sounds but some dickhead(s) wrote an application that will generate random email addresses at an amazing rate, then send them out. Now with the amount of people online you can write just about anything in an email address and you'll hit one or more valid addresses. Last I heard it was something like 1,000,000 spam emails are being sent out every second...
One good thing about spam though is payback. If there is someone you positively hate, one way to nail them is to find out all their addresses and put them on every promo list you can find. There are sites online for this believe it or not. I've done this to a couple of people and eventually they have to change their email address due to the 700 spams they were getting every hour....If I remember correctly the last person I did this to had 10,000 emails in their inbox the next morning when they came to work.
there are also options in microsoft outlook filters that move junk email to your deleted emails folder which can be dumped whenever you sign off outlook but you will still receive spam exponentially if the spammers think your email address is valid and this could use up your bandwidth costing you $$ if you go over your monthly limit.
The only way to stop spam is to change your email.
Personally, and this may be extreme, but I think that any company, anywhere in the world, who sends out unsolicited emails should have 3 warnings, if after 3 warnings they continue to do this they should immediately have their bank accounts frozen and the company closed.
This goes for writers of trojans/virus' etc. If they are caught they should face a stiff jail sentence.....