When and admin sends a direct email to a customer, the secret admin URL is revealed in the standard copyright notice at the bottom of the email message.
The reason for this is that the default language file(s) use the function that constructs a URL to the admin site instead of a store URL.
Solution: find the define for EMAIL_FOOTER_COPYRIGHT in admin/includes/langugages/*/email_extras.php and replace zen_href_link(FILENAME_DEFAULT) with zen_catalog_href_link(FILENAME_DEFAULT)
Please fix this minor problem in the next release.
Arjan



