33. A server system, for processing messages, comprising: one or more processing units for executing programs; memory storing one or more programs be executed by the one or more processing units; the one or more programs comprising instructions for: receiving a plurality of messages directed to a user, each message having a unique message identifier; associating each of the plurality of messages with a respective conversation; associating with each conversation a sender list, the sender list identifying a set of senders of messages included in the conversation; and providing presentation information for displaying a list of conversations and their associated sender lists comprising a set of rows, wherein the presentation information is formatted such that: conversation identifying information for each conversation in the list of conversations is displayed as a single row in the set of rows; and the sender list associated with the conversation is displayed in the same single row, along with the conversation identifying information; and wherein a displayed 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.
33. A server system, for processing messages, comprising: one or more processing units for executing programs; memory storing one or more programs be executed by the one or more processing units; the one or more programs comprising instructions for: receiving a plurality of messages directed to a user, each message having a unique message identifier; associating each of the plurality of messages with a respective conversation; associating with each conversation a sender list, the sender list identifying a set of senders of messages included in the conversation; and providing presentation information for displaying a list of conversations and their associated sender lists comprising a set of rows, wherein the presentation information is formatted such that: conversation identifying information for each conversation in the list of conversations is displayed as a single row in the set of rows; and the sender list associated with the conversation is displayed in the same single row, along with the conversation identifying information; and wherein a displayed 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. 38. The server system of claim 33 , wherein at least one row in the set of rows includes a recipient indicator that indicates whether the user is a primary recipient or secondary recipient of any message in the conversation.