Note to self: Finally figured out how to get Mail.app on OS X Mavericks to behave when I am trying to delete or move mailboxes that are “On My Mac”. The Secret is there was an ACL set that was preventing the everyone group from deleting anything.

ls -le
total 0
drwxrwxr--  16 joe  staff  578 Feb 27 08:56 V2
0: group:everyone deny delete

There may be undesired consequences from doing this…proceed at your own risk.

To fix this:

1. Quit out of Mail.app

2. Open terminal, and do the following.

cd ~/Library/mail
chmod -R -a "everyone deny delete" V2

That will remove the ACL from all of the mailboxes and folders.  As I said, might have a negative side effect.

I’d like to thank Vincent Danen for the article he wrote at TechRepublic.com that pointed me in the right direction.