Apple Mail: undo Use This Mailbox For...

[Eric Gorr]

I'm using the latest version of Apple Mail with an IMAP account.

I selected a folder and then selected Use This Mailbox For (in the  
Mailbox menu), but selected the wrong item in the menu (selected  
Drafts instead of Sent).

Is there any way to undo this selection?

I'm probably missing something obvious, but a solution is not  
presenting itself to me at the moment.