Deletes a folder from the account. (WARNING: This will delete all the mail stored in the folder. This account cannot be undone!)
{"msg":"Mail","action":"DeleteFolder","folder_name":"family"}

If the folder exists in the account:
{"MSG":"MailFolderDeleted"}

If the folder doesn't exists in the account:
{"MSG":"MailFolderNotFound"}

If you are not logged in:
{"MSG":"MailLoginRequired"}