1. A method comprising: by a computing device, analyzing a message to perform sentiment analysis with respect to at least a portion of the message, the message being composed by an author of the message for a recipient of the message, wherein the message is associated with a target mentioned in the message, wherein the target mentioned in the message is a person other than the recipient of the message who is mentioned in the message, and wherein the target mentioned in the message has a social relationship with the author of the message, the social relationship being determined based on a social graph comprising social-graph nodes corresponding to the author of the message and the target mentioned in the message and further comprising social-graph edges connecting the social-graph nodes; by the computing device, identifying one or more sentiments associated with the at least a portion of the message; by the computing device, determining one or more ideograms based on the social relationship between the author of the message and the target mentioned in the message and further based on ideogram usage history associated with the author of the message in which the author previously manually selected an ideogram other than a suggested ideogram and ideogram usage history associated with one or more other users that match profile information of the author of the message and that have a social relationship with the author, wherein each ideogram corresponds to an identified sentiment; and by the computing device, suggesting one or more of the one or more determined ideograms.