1. A method for generating a personalized reaction, the method comprising: determining, using one or more computing devices, interaction items associated with a first user from a data source, the interaction items associated with the first user including an online user post and the data source including an online service; determining, using the one or more computing devices, interaction items associated with other users from the data source; processing, using the one or more computing devices, the determined interaction items associated with the first user to produce one or more message labels; ranking, using the one or more computing devices, the message labels; automatically generating, using the one or more computing devices, a suggested personalized reaction in response to a message associated with the other users based on content of the message using a decision tree, the ranked message labels, and the determined interaction items associated with the other users; receiving, using the one or more computing devices, a user input associated with the suggested personalized reaction; and processing, using the one or more computing devices, the user input to update the decision tree.