A system and related method are disclosed for establishing geographical communication and predicting mail delivery using mailbox-mounted devices adapted to detect delivery automatically and transmit that detection to associated electronic devices. Detection may be performed by various means including accelerometers, cameras, and magnetometers. The method includes maintaining a registry of mailbox-mounted devices, and passing communication between electronic devices used by owners of mailbox-mounted devices. The communication can include detection by the mailbox-mounted devices of mail delivery, and calculation of the postal carrier's probable route using that delivery detection.