1. A method comprising: receiving a query by a computing device; determining a plurality of discussion groups that are relevant to the query by the computing device, wherein each discussion group is associated with a plurality of messages and each message is associated with an author; for each discussion group of the plurality of discussion groups, determining an authority score for each author associated with a message of the discussion group by the computing device; for each author associated with a message, determining a preference score for the author for each discussion group of the plurality of discussion groups by the computing device; and ranking the discussion groups of the plurality of discussion groups using the preference scores and the authority scores by the computing device.