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. 46. The computer readable storage medium of claim 43 , wherein the instructions for providing presentation information including instructions that, when the conversation corresponding to the row includes a message sent by a first sender and one or more messages sent by a second sender, provide in a first distinct format an identifier of the first sender in the sender list when the message sent by the first sender has not been viewed or marked as read by the user, and provide in second distinct format an identifier of the second sender in the sender list when all the messages sent by the second sender have been viewed or marked as read by the user.