New answers tagged imap
In the Menu Bar, go to Mailbox after selecting the sub-mailbox, one of your Sent folders, for instance, and then choose "Use This Mailbox For…". You can lump the redundancies together this way, but it's true that you will not be able to completely customize all the boxes.
The Mailboxes that are created by Mail app can not be modfied. Only Mailboxes that you created can be modified. Thus: Inbox, Draft, Sent, Junk, Trash, Archive and "on My Mac mailboxes" can not be modified.
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