US Patent 9876753 Automated message security scanner detection system

An electronic messaging system includes a messaging server that identifies a recipient for an electronic message. The messaging system sends the recipient an electronic message that includes instrumented content. A web server monitors activity and determines whether interaction occurred with the instrumented content. The web server determines whether a sandbox intercepted the message based on whether interaction occurred, or did not occur, with the instrumented content within a threshold time period or with one or more activity characteristics.