Documentation proposal for mailbox config

[evolvedlight]

We've set this up but the volume of "spam" we have in the default mailbox is a bit high. I tried creating a new mailbox that would take the "spam". However, now both the default and the seperate mailbox have a copy of the spam.

Would you accept a PR that would let us configure that the default mailbox doesn't get all mails, if they are routed to another mailbox?
Otherwise we need to override the recipients of the default mailbox with a negative regex

[evolvedlight]

Hey, sorry, this is not true. It already works like this.
Instead, can I propose improvements to documentation for the mailbox configs? or you'd prefer people to check the appsettings.json for their version?