You can read a thread on here about spam http://forum.camping.com.au/viewtopic.php?t=2250&highlight=
but unless you have a very good spam filtering system you will end up getting some spam eventually.
You can reduce your chances of getting spam somewhat by:
1) Never post your email address on a website such as a forum etc
2) Don't forward those stupid chain mails such as "if you forward this to 10 people you will get 3 years good luck etc"
3) don't reply to any message that you don't recognize as a friendly one.
4) never click on a "unsubscribe" link in an email unless you know 100% that you did subscribe with them in the first place.
5) Avoid opening an email that is unrecognized
6) Never click on a link in an email unless your are 1000000% sure it is safe.