19. The method of claim 2 further comprising: providing the content of the selected conversation including text formatted so as to differentiate between first messages of the selected conversation and second messages of the selected conversation by highlighting the text matching the search query in the first messages.
2. A computer-implemented method performed at a server_system having one or more processors and memory, the method comprising: responding to a single search query, including: searching a message repository to identify a plurality of conversations that each include at least one message 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; sending 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 including text formatted so as to differentiate between first messages of the selected conversation and second messages of the selected conversation, wherein the first messages include text matching the search query and the second messages do not include text matching the search query; and providing formatting information for the first messages in a first format and providing formatting information for the second messages in a second format; wherein the first format differs from the second format in a visually distinctive manner.