Web mail search is an emerging topic, which has not been the object of as many studies as traditional Web search. In particular, little is known about the characteristics of mail searchers and of the queries they issue. We study here the characteristics of Web mail searchers, and explore how demographic signals such as location, age, gender, and inferred income, influence their search behavior. We try to understand for instance, whether women exhibit different mail search patterns than men, or whether senior people formulate more precise queries than younger people. We compare our results, obtained from the analysis of a Yahoo Web mail search query log, to similar work conducted in Web and Twitter search. In addition, we demonstrate the value of the user's personal query log, as well as of the global query log and of the demographic signals, in a key search task: dynamic query auto-completion.
We discuss how going beyond users' personal query logs (their search history) significantly improves the quality of suggestions, in spite of the fact that a user's mailbox is perceived as being highly personal. In particular, we note the striking value of demographic features for queries relating to companies/organizations, thus verifying our assumption that query completion benefits from leveraging queries issued by ``people like me". We believe that demographics and other such global features can be leveraged in other mail applications, and hope that this work is a first step in this direction.