Mail.app in OS X — IMAP and Archive Mailbox subfolder creation

I am using Mail.app with an IMAP .com email address:

For some reason, at 10.9, Mail changed and now the special "Archive" Mailbox doesn't allow for new subfolders to be added within the "Archive".

It isn't possible to add subfolders via a menu or to drag existing folders into the Archive.

Solution 1:

The only workaround I have found to add subfolders to the Archive mailbox is to add a new Mailbox (in Sidebar for the IMAP Account, Right click / New Mailbox…) Choose the account and for the name box enter:

Archive/"Name of the New Folder" (without quotes, remember the slash!)

This will create a new subfolder within Archive. :)

Anyone know any other way?

Solution 2:

Under Mojave I was able to create a new mailbox that was "On My Mac" with multiple folders. I am able to create subfolders under those folders.