I get so much SPAM

Editor's note: Basically, this discussion is only here for historical record. Our SpamAssassin, greylisting and blocklisting policies mean GreenNet users now have very little problem with spam. For information correct as at 2009, see:

• A guide to Spam
• How to avoid email Spam
• A breakdown of email received and blocked, Jan 2008

I am just receiving too many Spams, Porno sites, people wanting account details while offering to share millions of dollars and people trying to sell, all of these unsolicited and obviously able to come through the GreenNet portal. The rubbish flooding into my mailbox is just too much for me to cope with. What does GreenNet do against spam?