I've set up SPF checking on my postfix gateway and have confirmed that messages from domains set with hard fails that don't come from a good sender are rejected outright. Messages from domains set with a softfail that come from bad sources are tagged in the message header with "Softfail (domain owner discourages use of this host)", but end up in the user's Inbox, anyway. I suppose I kind of figured DoceCot would see the SPF softfail in the message header and automagically route that message to Junk, but it didn't.

I've looked around Google and the Dovecot documentation to see if there are any instructions on how to do this, but I can't find anything. Is there an easy way to do this or do I need something more advanced in the way of a spam filtering system? OR is doing this my mail client's responsibility and I need to look around my Thunderbird settings? I suppose it's also possible that Postfix needed to do something beyond adding the Received-SPF line in the message header, but I didn't see anything about that in the Policy-SPF config. This is my first foray into SPF so I'm open to any suggestions.