A method of synchronization control of folders containing emails in a first electronic mailbox hosted by a first server and folders in a second electronic mailbox hosted on a second server in a computing system, the first electronic mailbox being replicated from the second electronic mailbox, wherein the method comprising: receiving data representing signals indicating an interaction of a user with an email in a first folder in the first electronic mailbox or an interaction of a user with the first folder directly; and a failure of performing a synchronization operation between a second folder in the first electronic mailbox at the first server and a corresponding folder of the second electronic mailbox at the second server; and upon receiving the interaction signals, calculating a prioritization score corresponding to each of the first and second folders based on the interaction and failure indicated in the received signals, wherein calculating the prioritization score corresponding to each of the first and second folders based on the interaction and failure indicated in the received signals includes: assigning a first score to the interaction of the first folder and a second score to the failure corresponding to the second folder; and deriving a first prioritization score by summing the assigned first score with other scores assigned to additional interactions or failures corresponding to the first folder; and deriving a second prioritization score by summing the assigned second score with further scores assigned to additional interactions or failures corresponding to the second folder; performing a comparison of the calculated prioritization scores of the first and second folders; and based on the performed comparison, synchronizing the first folder at the first electronic mailbox hosted at the first server with another corresponding folder at the second electronic mailbox hosted at the second server according to a first synchronization rule and the second folder at the first electronic mailbox with the corresponding folder at the second electronic mailbox according to a second synchronization rule different than the first synchronization rule. receiving data representing signals indicating an interaction of a user with an email in a first folder in the first electronic mailbox or an interaction of a user with the first folder directly; and a failure of performing a synchronization operation between a second folder in the first electronic mailbox at the first server and a corresponding folder of the second electronic mailbox at the second server; and an interaction of a user with an email in a first folder in the first electronic mailbox or an interaction of a user with the first folder directly; and a failure of performing a synchronization operation between a second folder in the first electronic mailbox at the first server and a corresponding folder of the second electronic mailbox at the second server; and upon receiving the interaction signals, calculating a prioritization score corresponding to each of the first and second folders based on the interaction and failure indicated in the received signals, wherein calculating the prioritization score corresponding to each of the first and second folders based on the interaction and failure indicated in the received signals includes: assigning a first score to the interaction of the first folder and a second score to the failure corresponding to the second folder; and deriving a first prioritization score by summing the assigned first score with other scores assigned to additional interactions or failures corresponding to the first folder; and deriving a second prioritization score by summing the assigned second score with further scores assigned to additional interactions or failures corresponding to the second folder; assigning a first score to the interaction of the first folder and a second score to the failure corresponding to the second folder; and deriving a first prioritization score by summing the assigned first score with other scores assigned to additional interactions or failures corresponding to the first folder; and deriving a second prioritization score by summing the assigned second score with further scores assigned to additional interactions or failures corresponding to the second folder; performing a comparison of the calculated prioritization scores of the first and second folders; and based on the performed comparison, synchronizing the first folder at the first electronic mailbox hosted at the first server with another corresponding folder at the second electronic mailbox hosted at the second server according to a first synchronization rule and the second folder at the first electronic mailbox with the corresponding folder at the second electronic mailbox according to a second synchronization rule different than the first synchronization rule.