1. A computer-implemented method inserting messages in a message sharing system, comprising: receiving electronic messages posted by a plurality of posting users; receiving interaction information for each of the electronic messages, the interaction information comprising an indication of at least one of information within the electronic message, a posting user of the electronic message and a following user of the electronic message; determining a score for each electronic message based on the interaction information for the electronic message; selecting, based on the determined scores, one or more electronic messages for insertion into a message stream of a user; and transmitting the selected electronic messages to the user for insertion into the message stream of the user.