17. A computer-implemented method comprising: at a server, responding to a single search query received from a client, including: searching a message repository to identify a plurality of conversations relevant to the search query, wherein each of the plurality of the identified conversations includes one or more messages sharing a common set of characteristics that meet predefined criteria, and wherein each of the plurality of the identified conversations includes a respective conversation identifier, and sending to the client a list of conversations representing at least a subset of the identified conversations, wherein at least one of the conversations in the list includes a plurality of email messages; providing content of a selected conversation from the list of conversations to the client, wherein the provided content includes text formatted so as to differentiate between first text of the selected conversation and second text of the selected conversation; wherein the second text includes text matching the search query and the first text does not include text matching the search query; and providing formatting information for the first text in a first format and providing formatting information for the second text in a second format; wherein the first format differs from the second format in a visually distinctive manner.
17. A computer-implemented method comprising: at a server, responding to a single search query received from a client, including: searching a message repository to identify a plurality of conversations relevant to the search query, wherein each of the plurality of the identified conversations includes one or more messages sharing a common set of characteristics that meet predefined criteria, and wherein each of the plurality of the identified conversations includes a respective conversation identifier, and sending to the client a list of conversations representing at least a subset of the identified conversations, wherein at least one of the conversations in the list includes a plurality of email messages; providing content of a selected conversation from the list of conversations to the client, wherein the provided content includes text formatted so as to differentiate between first text of the selected conversation and second text of the selected conversation; wherein the second text includes text matching the search query and the first text does not include text matching the search query; and providing formatting information for the first text in a first format and providing formatting information for the second text in a second format; wherein the first format differs from the second format in a visually distinctive manner. 25. The method of claim 17 , further comprising: providing the content of the selected conversation to the client, including highlighting the second text that includes text matching the search query.