YouTuber James Music has shown off a neat project which lets them know whenever they receive mail. Technically, this isn’t an ESPHome project as they have used Tasmota flashed on to a LOLIN D1 mini, but since ESPHome also supports servos it should be possible to port. Though, the creator has mentioned on Reddit that they had problems doing so.
You will have to have made your actual mailbox smart for this project to work. Home Assistant needs to somehow know whether you have got mail. The original creator uses door break sensors, but the same could be done using a cleverly placed Aqara door/window sensor.
Parts needed for the mini mailbox
This project requires that you own or have access to a 3D printer. The mini mailbox itself is 3D-printed and all the parts are available on Thingiverse. You will also need a LOLIN/Wemos D1 mini, an SG90 9G servo, some wires, and a soldering stations. If you want to go the extra mile, you can paint the mini mailbox or print it using different coloured filaments.