Agents can create new inboxes and inboxes can be of 3 types, besides "Permanent" which is just a regular inbox. The other types don't have "rules" that you can customize. Instead the rules are baked-in: Temporary -> expires after some time, One-sender: allows only one sender (the first one to prove its email identity), Prefix: similar to one-sender but creates a new inbox for every suffix (and if spammers catch on to the prefix, you can delete it and create a new one).