1. A method comprising: at a computing device having one or more processors and memory storing one or more programs configured for execution by the one or more processors: displaying an indication of an electronic message to a receiving user within a cluster graphic corresponding to a first message cluster in a plurality of message clusters, wherein the first message cluster includes a plurality of electronic messages, and wherein the plurality of message clusters is in an inbox folder; detecting that the receiving user has read at least a portion of the electronic message other than the indication of the electronic message; determining whether the receiving user has taken an affirmative action to retain the indication of the electronic message in the cluster graphic within a predefined time period after detecting that the receiving user has read at least a portion of the electronic message, wherein the affirmative action comprises pinning the electronic message or flagging the electronic message to be kept; when it is determined that the receiving user has not taken the affirmative action, automatically removing the indication of the electronic message from the cluster graphic and automatically removing the electronic message from the message inbox to an archive or delete folder; and when it is determined that the receiving user has taken the affirmative action, retaining the indication of the electronic message in the cluster graphic.