New accounts are succesfull added into Contact Lists. But in notification email I see string:
New Subscribers: 0
What does it mean?
If you are using ACTION_BY_CUSTOMER, you will never see any counts in your new subscriber email notification. You will only see contacts who are added with the value ACTION_BY_CONTACT. This does not include anyone added by the Bulk Activity API as well as those are all put in as ACTION_BY_CUSTOMER due to the nature of bulk activities (meaning contacts would never request to have 25 or more addresses added or updated at once.