Don't Delete This Message -- Folder Internal Data
From: "Mail System Internal Data [MAILER-DAEMON@ooorah]"
Subject: "DON'T DELETE THIS MESSAGE -- FOLDER INTERNAL DATA"
"This text is part of the internal format of your mail folder, and is not
a real message. It is created automatically by the mail system software.
If deleted, important folder data will be lost, and it will be re-created
with the data reset to initial values."
Why does this keep returning to my inbox? Is it real or is it SPAM?