http://spamlinks.net/ - this page contains links to all the information you will need on spam.
Spam is growing exponentially year on year. The economics of spam make it a low cost profitable business. Here are some statistics on the current extent and future of this problem (supplied by ePrivacy Group).
At a governmental level, legislation is being introduced in an attempt to make spam illegal. However there is much debate about this approach and little agreement between countries. Add, to this the difficulties in tracing spammers and their disrespect for the law. It seems spam is with us for the forseeable future.
Because the legal route is slow and troublesome, fighting spam on the technical level is the best option available. This has given rise to a multitude of organisations, software, and techniques which all aim to fight off the worldwide growth of spam.
It seems that masking email addresses and ISP spam filtering
may be having and effect on spam ....
http://www.ftc.gov/opa/2005/11/spamharvest.pdf