43. A computer readable storage medium storing one or more programs for execution by one or more processors of a computer system, the computer readable storage medium being non-transitory, the one or more programs in the computer readable storage medium comprising: instructions for receiving a plurality of messages directed to a user, each message having a unique message identifier; instructions for associating each of the plurality of messages with a respective conversation, each conversation having a respective conversation identifier; wherein each conversation comprises a set of one or more messages sharing a common set of characteristics that meet first predefined criteria and the respective conversation identifier is distinct from a subject reference of the one or more messages in the respective conversation; instructions for associating with each conversation a set of senders of messages included in the conversation; and instructions for providing presentation information for displaying a list of conversations in an order determined in accordance with second predefined criteria, each conversation being represented as a single item in the list, wherein a plurality of conversations in the list of conversations each include a plurality of messages that share a common set of characteristics that meet the first predefined criteria; wherein the instructions for providing presentation information include instructions for providing information to display the list of conversations as a set of rows, each row corresponding to one of the listed conversations and including at least a sender list, a conversation topic and a date/time value, wherein the sender list of a row in the list of conversations includes identifiers of one or more senders of at least one message in the corresponding conversation, including identifiers of a plurality of the senders in the set of senders, but less than all of the senders in the set of senders, when the set of senders exceeds a predefined limit.
43. A computer readable storage medium storing one or more programs for execution by one or more processors of a computer system, the computer readable storage medium being non-transitory, the one or more programs in the computer readable storage medium comprising: instructions for receiving a plurality of messages directed to a user, each message having a unique message identifier; instructions for associating each of the plurality of messages with a respective conversation, each conversation having a respective conversation identifier; wherein each conversation comprises a set of one or more messages sharing a common set of characteristics that meet first predefined criteria and the respective conversation identifier is distinct from a subject reference of the one or more messages in the respective conversation; instructions for associating with each conversation a set of senders of messages included in the conversation; and instructions for providing presentation information for displaying a list of conversations in an order determined in accordance with second predefined criteria, each conversation being represented as a single item in the list, wherein a plurality of conversations in the list of conversations each include a plurality of messages that share a common set of characteristics that meet the first predefined criteria; wherein the instructions for providing presentation information include instructions for providing information to display the list of conversations as a set of rows, each row corresponding to one of the listed conversations and including at least a sender list, a conversation topic and a date/time value, wherein the sender list of a row in the list of conversations includes identifiers of one or more senders of at least one message in the corresponding conversation, including identifiers of a plurality of the senders in the set of senders, but less than all of the senders in the set of senders, when the set of senders exceeds a predefined limit. 55. The computer readable storage medium of claim 43 , wherein each row in the list of conversations comprises said single item representing a respective conversation, and the sender list of at least one respective conversation in the list of conversations identifies two or more distinct senders of messages in the respective conversation.