Mailbox key not returned by the tenant

[Farnaz Z.]

Hello BP landlords,

My property’s mailbox keys were not returned by the previous tenants and my management company is saying that they can not get my mailbox keys until a new tenant is in the property so they can request a key with a copy of the lease. 
is there any way I can request a mailbox key from the USPS before my unit is rented?

I’m an out of state landlord so can not physically go to the USPS office.

Thank you for your guidance on this matter…

P.S. the USPS owns my mailbox