Move spam messages to spam mailbox

[miaulalala]

Feature Request

We currently don't do anything on makring a message as spam/junk. Add a setting that will automatically move a message to the spam / junk folder on marking it as such.

[ChristophWurst]

I would argue this could be the default. But let's check the RFCs as I'm sure there are guidelines for how email clients should handle this

[miaulalala]

This will also mean adding a default folder for junk I assume?

[ChristophWurst]

Yes, we need a setting for the preferred junk mailbox like we have for draft, sent and trash.

[ChristophWurst]

Dup of #4101