Sending an Email from a Journey Builder Interaction to a Subscriber not in All Subscribers

Question

We have created a Journey that sends an email when a new subscriber is added to a data extension. We then fire the event from the REST API. This all works fine except when the new Subscriber does not already exist in All Subscribers.

If the Subscriber exists in All Subscribers the subscriber enters the Journey and the email is sent.

If the Subscriber does not exist in All Subscribers the subscriber enters the Journey and looks like everything runs through except the email is never sent.

My initial thought was to add the Subscriber to All Subscribers, but I don't see a REST Route to add a Subscriber. This seems like it would be a very common use case. What am I missing?

Answer 1

When creating the Link Data Extension in Contact Builder you need to set it up as a one-to-one relationship. This gives you the option to use the Data Extension as root (this is a checkbox). This option is not available if you use a one-to-many relationship.

Once you have the root checkbox checked then the new subscriber will be added to All Subscribers and the email will be sent.