He's got a weird sleep schedule, though, so chances are he'll be asleep when I get home. I suggested that once he gets into the building and apartment with my keys, he picks up his key, puts my two keys inside the mailbox with his mailbox key, and I open up the mailbox with my mailbox key to retrieve my two keys.
As he was leaving I realized I wouldn't be able to even enter my building to access the mailbox if he had my building key, but then I remembered that my cell phone is also a key - I just use the numpad at the building door to dial my phone and unlock the door.
I took the elevator back to my office floor, and tried opening the front door to my office - locked. As a contractor, I don't have a keycard. Fortunately, a round of loud knocking alerted someone and they let me in.
My head hurts.