14. A non-transitory computer readable storage medium and one or more computer programs embedded therein the one or more computer programs comprising instructions which, when executed by a computer system, cause the computer system to: receive a plurality of messages directed to a particular user; determining a respective conversation for each of the plurality of messages; send to a client system for display a first list of conversations including the respective conversation, as a set of rows, each row corresponding to one of the listed conversations and including at least a sender list configured by the computer system to include only identifiers of senders of messages in the conversation corresponding to the row; enable the particular user to identify one or more conversations in the first list of conversations, and to mark the identified one or more conversations as belonging to a particular category while continuing to display at least a portion of the first list of conversations, which includes the identified one or more conversations; and send to the client system for display a second list of conversations.
14. A non-transitory computer readable storage medium and one or more computer programs embedded therein the one or more computer programs comprising instructions which, when executed by a computer system, cause the computer system to: receive a plurality of messages directed to a particular user; determining a respective conversation for each of the plurality of messages; send to a client system for display a first list of conversations including the respective conversation, as a set of rows, each row corresponding to one of the listed conversations and including at least a sender list configured by the computer system to include only identifiers of senders of messages in the conversation corresponding to the row; enable the particular user to identify one or more conversations in the first list of conversations, and to mark the identified one or more conversations as belonging to a particular category while continuing to display at least a portion of the first list of conversations, which includes the identified one or more conversations; and send to the client system for display a second list of conversations. 17. The non-transitory computer readable storage medium of claim 14 , wherein the second list of conversations is produced by executing a corresponding search query.