Mail.app allows you to organize your messages into folders and sub-folders. This is frequently combined with Rules for automatic sorting of incoming messages. Visually in Apple Mail, there are two kinds of folders: a blue icon folder (mailbox) can contain messages and sub-folders, while a white icon folder (folder) can only contain sub-folders (more info on mailbox colors). Or, so I thought.
Today, I received an email which was automatically sorted into one of my folders, called "Website." The problem was that when I created the rule, Website was a mailbox (blue icon), but had since become a folder (white icon). Yet, there was the Website folder staring me in the face, in bold and with "(1)" appended telling me that there was a new message in there for me to read. But, I could't read it. After some playing around, I found a solution using both Mail and Terminal.
cp Incoming_Mail A.mbox/mbox
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