Sending content between client devices connected to a computer network is described. According to one described aspect, a server maintains a database correlating unique identifiers for client devices to their network address information. A first client device may query the server for network address information of a second client device by sending the unique identifier to the server. The server returns the network address of the second client device, which is used to send a message directly from the first client device to the second client device, indicating the availability of content. Also, the message is preferably formatted such that it automatically populates a content guide of the second client device, with an entry used to initiate a transmission of the content from the first client device to the second client device.