A system in which a message from a server is transmitted to a recipient device, the message including an image reference that identifies the location of an image. A request is received for the image file from the recipient device. The image file is transmitted to the recipient device and a start time of the transmitting is noted. Upon detecting that the image file has ceased being transmitted, an end time of the transmission is noted. The end time and start time are compared to make a determination of whether the message was read.