Can I access Gmail's spam message folder using pop3/imap?
With IMAP, yes. The Spam folder is available as [Gmail]/Spam.
POP3 is very limited, and only allows accessing messages from INBOX. This is limitation of POP3 itself.
If you need to access spam messages using pop3, you can create a filter to never place e-mail in the spam folder. According to http://aaron-kelley.net/blog/2008/08/disable-gmail-spam-filter-include-spam-in-pop3-download/
- Go to gmail.com
- Create a new filter
- Type * in the From field
- In the next screen, select "Never send it to spam"
- POP3 now downloads spam too