deadmanssnitch-google-apps-gmail.gs

function DeadMansSwitchGmailCheckIn() {
  var messages = Gmail.Users.Messages.list("me", { q: "from: no-reply@example.com label:unread" });
  
  if (messages.messages && messages.messages.length > 0) {
    Logger.log(UrlFetchApp.fetch("Your Snitch URL"));
    
    for (var i = 0; i < messages.messages.length; i++) {
      var message = messages.messages[i];
      Gmail.Users.Messages.modify({"removeLabelIds": ["UNREAD"]}, "me", message.id);
    }
  }
}