1. A computer-implemented method for disseminating messages to a respective user in a messaging system, comprising: in a server system having one or more processors and memory storing one or more programs for execution by the one or more processors, the computer-implemented method comprising: selecting, from a plurality of message threads, a set of messages based at least in part on a focus specification associated with the respective user, the focus specification comprising one or more selection criteria specified by the respective user; sending to a respective client system associated with the respective user target messages comprising at least a subset of the selected set of messages; receiving a user selection of one or more messages in the target messages as one or more anchor messages; sending to the respective user messages in one or more threads associated with the one or more anchor messages, subsequent to the one or more anchor messages, as tracked messages; and sending to the respective client system one or more instructions to display an author indication control for allowing the respective user to indicate interest in an author.