According to another web site:
"All e-mail items from addresses and Internet domains that are junked
through Junk Mail Handling are placed in the Junk Mail folder. This folder is
not created in the folder list unless a Junk Mail option is enabled.
While Junk Mail options are enabled, this folder cannot be deleted. However,
the folder can be renamed or moved to a different location in the folder
list. If all Junk Mail options are disabled, the folder can be deleted. The
folder can also be deleted if the Junk Mail Handling feature is disabled by
the system administrator."
Not really a complete answer, but maybe that will help you find the full
answer.