django_registration (at least the 0.7 version that is listed as required by satchmo) uses the django core send_mail wrapper function and provides "settings.DEFAULT_FROM_EMAIL" as part of the create_inactive_user() function. Effectively this bypasses the shop configuration since there isn't a way to pass in the store_email.
So, apparently we need a duplicate (triplicate?) configuration for email settings...
1) store_email in the livesettings shop config
2) if not #1, satchmo uses the first listed email in settings.ADMINS (and I guess the ADMINS emails are also used elsewhere)
3) settings.DEFAULT_FROM_EMAIL to handle usage by django_registration