I have many folders that are populated by redirection from my web hosting site. SS is not checking those folders for spam. How do I set it up so it does?
Which mail client are you using with SpamSieve?
Could you clarify how the messages are being redirected?
I am using OS X Mail for an email client… I use a web hosting service where I have several websites hosted… each has one or two email accounts, which are redirected to my personal account which is on fastmail.us. At fastmail, defined rules put them into the correct folders.
Apple Mail can only process message that arrive in the inbox. So if the server is depositing the messages into other IMAP mailboxes, they’ll be invisible to SpamSieve and your other rules. You could either:
- Set up Mail to check the accounts directly; or
- Change your server rules so that the messages go to the inbox; or
- Use a mail program such as Outlook that can apply rules to messages that arrive outside the inbox.
How do I setup Mail to check the accounts directly? (a URL to a doc would help) 
You’ve already set up Mail to check your personal account. You would just need to find the corresponding server/name/password info for the other accounts and enter those the same way. You may need to configure the server to create separate mailboxes/accounts for these addresses instead having an alias/forwarder. The specifics would depend on your Web hosting provider.