SS Trunk with User Defined Forms Trunk. If I set define('SS_SEND_ALL_EMAILS_TO', ''); then any email addresses I have set up for the form to send to do not get sent. I don't know if this is the intended behavior or not. I would hope that the admin would just get copied on the emails sent from the forms and not replace all email addresses that are set up for the form.
define('SS_SEND_ALL_EMAILS_TO', '') is designed for while testing you do not send emails out to other members. This came round after emailing a 10,000 user base with a couple of test emails. Its not designed for use on a live site