Extension specifically for searching mailboxes.

Hi.

I often search for a specific folder (mailbox) in Mail. For example, when I can’t quite remember where that email is, or when I want to move an email to a specific mailbox.

What I’m looking for is an extension that allows me to search through mailboxes, not the contents of the mailboxes, but only the names of the mailboxes themselves.

Ideally, it would be a search field at the top of the folder list. Does anyone know of such an extension?