6. A conversation-based message system, comprising: one or more conversation servers, the one or more conversation servers comprising: memory; one or more processors; and one or more programs stored in the memory and configured to be executed by the one or more processors, the one or more programs including: instructions for associating, according to predefined criteria, at least one of a plurality of received messages to a conversation from a plurality of conversations, each of the plurality of conversations having at least one message and a respective conversation identifier, wherein the predefined criteria includes a subject of the one or more messages and information other than the subject of the one or more messages; instructions for storing in a message storage system messages and associated information, including conversation information; instructions for producing a list of conversations in response to a search query, each conversation in the list being represented as a single item in the list of conversations, at least one of the conversations in the list comprising two or more electronic messages from distinct senders; instructions for creating formatting information associated with at least one of the conversations in the list of conversations that differentiates those messages in a conversation relevant to the search query from those messages that are not relevant to the search query and includes text information from at least one message relevant to the search query; and instructions for returning a search result which includes the list of conversations and the formatting information.
10. The system of claim 6 , wherein the one or more programs further comprise instructions for producing formatting information associated with the conversation topic of a respective conversation, such that, when displayed, the conversation topic is highlighted when the conversation includes at least one message that has not been viewed or marked as read by the user.