I will add this setting in the next version:
<add key="DisableWorkflowNotification" value="false" />
for now you could use this setting:
<!-- a comma separated list of email addresses to exclude when sending
administrative emails including registration notifications and content workflow submissions
this is for when you have admin user accounts that you do not want to receive these emails
-->
<add key="EmailAddressesToExcludeFromAdminNotifications" value="" />
Hope it helps,
Joe