How do Spammers get e-mail addresses?

Spammers use various means to obtain e-mail addresses. Among the ways used are:

1. Using automatic programs or "harvesters" to scan Newgroups, Webpages and Forwarded e-mails
2. Purchasing lists of e-mail addresses from third parties who compile such information.
3. Using 'dictionary attacks" to try out all possible combinations of letters, common names and words in e-mail addresses.