On the Razor settings page, is it possible to use IMAP to manage my mail, but still only have Razor add the X-Razor: SPAM heading to my mail, instead of filtering it to specific mailboxes? I'd like to do that client side if at all possible.
Sure... just select the POP3 option. You'll still be able to retrieve your mail via IMAP.
Cool. I thought as much, but really didn't fancy screwing up my mail account.