There are indeed numbers of anti spam software to deal with this spam threat, but the spammers have taken a step ahead by coming out with new spamming tactics such as PDF Spam and Piggyback Spam. The widely known form of spam is email spam. Email spam is a practice of sending unwanted emails frequently with commercial content in large quantities to the recipients. The total amount of email spam has reached 100 billions emails per day as at April 2008. Most of the email spams are being sent to invalid email address.
I was a victim of email spam and it happened just two weeks ago where I received an email on advertisement of IT products from a China company. Without my knowledge, this email is being sent to the recipients whom I do not know and even to all my friends. I received many postmaster fail notification everyday, around 80 emails of it. It was really frustrating and annoying but the worst part is sums of my important emails stored in my inbox suddenly disappear without any trace.
Besides that, a friend of mine who opened the email spam sent from my account found that all her contact list in her msn are gone the next few days. I manage to stop this spam by changing my password. I really hope that on day, an ultimate anti spam software will be developed to stop this spam once and for all.
Some useful links about spamming:-
http://www.ciac.org/ciac/bulletins/i-005c.shtml