mailman

Hello, I ordered an item that was sent through FedEx Smartpost, and I was told that after Smartpost hands the package to USPS, the package enters the system as parcel post mail. I was wondering if parcel post delivers the mail by the normal mailman that goes to your door daily to deliver mail...

Should I just stand beside the mail box or should I wait inside until he has delivered his package?

Two friends, Denis and Léo wish to communicate by mail. The mailman is dishonest. He steals. Each of the two friends has his own lock and key. They put their mail in a secure box. Question: How can Denis send a letter to Léo without the mailman opening the box?