I feel the same about my apartment door (my apartment was built in the 1970s), it has a mailbox attached to the inside of it and there is a slot in the door to put mail in it from the outside, it gets rarely used since most of the mail is delivered to the newer mailboxes installed by the stairs on the first floor, but If I’m not home, the delivery driver usually drops the slip in there.

However, below the mailbox is another, smaller, door that is intended specifically for newspapers. I tried to open it out of curiosity, but the latch was quite stiff and was painted over at some point, so probably the previous tenant also didn’t use it. That means that small door has probably been closed for at least a decade, if not more, and probably will remain closed forever.