1. A server system, for searching conversations, comprising: one or more processors; and memory storing one or more programs to be executed by the one or more processors; the one or more programs comprising instructions for: receiving a search query from a client; identifying a plurality of conversations relevant to the search query, the plurality of conversations including at least two conversations each having two or more messages sharing a common set of characteristics that meet predefined criteria and a respective conversation identifier; and returning to the client for display, as a search result to the search query, a list of the identified conversations, each conversation in the list being represented as a item in the list of conversations, at least one of the conversations in the list comprising two or more electronic messages from distinct senders.