From what sources do email spammers get their addresses?
Wikipedia mentions the following:
- Harvesting email addresses from publicly available sources.
- This includes web pages (web crawling), usenet posts, mailing list archives, DNS and WHOIS records
- Guessing email addresses (directory harvest attack)
- Asking people for their emails for one purpose, such as jokes of the day, and selling the email addresses elsewhere
- Getting access to people's address books (which Quechup utilized)
- Scanning an infected computer for email addresses.
Are there any other techniques used? Are any of the techniques above now obsolete?