Techniques are provided for secure and scalable electronic messaging. In one technique, a decision tree data and targeting criteria for a content delivery campaign are received and stored. Multiple entities that satisfy the targeting criteria are identified. First content from the decision tree data is retrieved and sent to a messaging account of each of the entities. The first content is presented in a message interface of a first entity. In response to detecting that the first entity has provided particular input, second content from the decision tree data is identified based on the particular input. First data associated with the particular input and the second content are presented in the messaging interface along with the first content.