A question about mail tampering?

So I have a concern. I live in the city and I have to rent a room in a big house. The bedrooms, living room, dining room, and even the garage are rented out to individual persons. The mail slot is on the garage door so the person who rents out the garage is the only person who has access to all the mail that gets delivered to the house. If this person were to withhold my mail or throw my mail in the trash, but not open my mail, is it still mail tampering? The mail is specifically addressed to me by the way. Even if it is not considered mail tampering, is it still against the law to withhold or throw away other people's mail, even though they reside in the address that is shown on the letter, postcard, etc.?