The Mailbox Reminder is designed for anyone who has regular or irregular mail service. It is an ideal device for people who make numerous trips to check the mailbox status daily. This Mailbox Reminder can eliminate the wasted trip to check the mail delivery, especially for people with health problems or disabilities. In addition, The wireless mailbox alert system is a security device to avoid stolen mail and indentity theft when the Mailbox is tampered or opened during non-delivery hours. Contents: ;Receiver Unit ;Sensor unit with mounting velcro ;6V DC adapter ;Instruction manual. Important note: The Mailbox Reminder is not for use on mailboxes with vertical hinges. The Mailbox Door must be closed in upright position. When installing the transmitter please note that the arrow should be pointing at you when you open the mailbox lid. This device is only to be used on a typical mailbox as shown in the image, it will not work on a vertical hinge mailbox.

A sensor linked to the home device attaches to the top of the mailbox. When the door is opened the sensor alerts the home device to tell you your mail has arrived. If you call our customer service, you can give your cell phone number to an operator who is also alerted when your mail arrives. The operator will send you a text message. You can choose to be alerted in your home, by cell phone, or both. On the home device you must press OK after you have taken your mail from the box, then the sensor will reset.
What I would Do Different
Instead of having a device in your home, I would create an app to lower the price.Add a feature where you could turn off the sensor and home device.

When your mailbox is opened, it sends a wireless signal out up to 300 feet to the receiver. The receiver gives you both a visual and an audio alert when the mailbox is accessed. The light will stay on until you reset it, ensuring that you definitely know that mail has been delivered.

With the mailbox alert system you can avoid unnecessary trips out to the mailbox. You can get an alert in case your mailbox is opened during non-delivery hours which can prevent stolen mail and possible identity theft. No need to continuously check outside to see if that passing vehicle was a mail truck or not. When your mail is delivered, you will know. Would also work if you use a similar style mailbox for your newspaper delivery.