At some point the USPS mailbox key may become lost and it’s unclear how to go about getting a new one, especially if the home is being rented.
In Minnesota, the resident living at the home needs to visit their nearby USPS location, not the home owner or property manager. At USPS, the resident will fill out a form and pay a small fee ($15 – $25?). Note, the resident must bring an ID showing their name and the property address on it. Within 4-5 days the lock on the mailbox will be changed and 3 keys will be provided to the resident. While at USPS, you may want to request mail to be held until the lock is changed.