1. A method comprising: receiving, at an online content management system from a remote uploading client computer via a network, a first block corresponding to a first block identifier in a blocklist corresponding to the content item; and responsive to receiving the first block at the online content management system and before receiving all blocks corresponding to the content item: obtaining a namespace identifier associated with the content item; identifying, by the online content management system, a remote receiving client computer associated with the namespace identifier; and sending, by the online content management system, the blocklist and the first block of the content item to the remote receiving client computer.