Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for receiving, by the one or more processors, user input, the user input indicating an assignment of a particular task by a first user to a second user, the first user being a user of a product that provides the particular task; determining, by the one or more processors, that the second user is a non-user of the product and, in response: appending product promotion data to an electronic document, the product promotion data providing a summary of task-based action data that is associated with the second user; and transmitting the electronic document to the second user.