Abstract: Email metadata, and in some embodiments other secondary data, is analyzed to identify users of interest defined as having knowledge or expertise in a subject matter. Specifically, a corpus of email metadata is analyzed to determine, at least, which subject matters are associated with users, which users received or transmitted subject matter-specific emails, the distribution groups to which users, and any other relevant email metadata. In additional embodiments, secondary data other than email metadata is also analyzed and used to identify the users of interest. The analyzed email metadate, and in some embodiments the secondary data, is used to render reputation indicator(s) for each user that indicate a level of knowledge/expertise that the user possesses on subject matter(s). A requester provides input criteria including the subject matter, and, in response, is presented a ranked user listing that is ranked based on the level of reputation indictor.