This disclosure covers systems and methods that verify a user's identity and generate automated messages within a messaging thread to prompt the user to digitally sign a digital document. Before generating such automated messages, the disclosed methods and systems optionally cause a client device to transition from presenting a newsfeed comprising a third party's digital content item to (alternatively or additionally) presenting a messaging thread. For instance, in some embodiments, the methods and systems provide a messaging thread for a user and the third party upon receiving a selection by the user of an option within the newsfeed associated with the digital content item. Within the messaging thread, the methods and systems then generate automated messages that prompt the user to digitally sign the digital document, such as a digital petition or contract.