use better defaults for ACE

playbooks/roles/edxapp/defaults/main.yml

@@ -237,10 +237,10 @@ EDXAPP_SOCIAL_AUTH_OAUTH_SECRETS: ""
 
 EDXAPP_ACE_CHANNEL_SAILTHRU_API_KEY: ""
 EDXAPP_ACE_CHANNEL_SAILTHRU_API_SECRET: ""
-EDXAPP_ACE_ENABLED_CHANNELS: []
-EDXAPP_ACE_ENABLED_POLICIES: []
+EDXAPP_ACE_ENABLED_CHANNELS: ["file_email"]
+EDXAPP_ACE_ENABLED_POLICIES: ["bulk_email_optout"]
 EDXAPP_ACE_CHANNEL_SAILTHRU_DEBUG: True
-EDXAPP_ACE_CHANNEL_SAILTHRU_TEMPLATE_NAME: !!null
+EDXAPP_ACE_CHANNEL_SAILTHRU_TEMPLATE_NAME: ""
 EDXAPP_ACE_ROUTING_KEY: 'edx.lms.core.low'
 
 # Display a language selector in the LMS/CMS header.