The previous tenant’s letters
What happens if you receive the previous tenant’s mail? Believe it or not, there is a correct protocol for dealing with this.
Take everything out of your mailbox and write “Return to sender” on it. Then put it back. Your mail carrier should see this and return the mail to its original sender, but it can’t hurt to let him or her know you’ve tried to return mail.
You can also write “moved” or “not at this address” on the letter which will let the post office know that the recipient is no longer at your address, but it will not necessarily return the letter to the original sender.
Then you just have to wait and hope that the companies pick up on the change or the resident changes their address. You may be tempted to throw the mail away, but don’t. Of course for ads and flyers or other obvious junk mail, it’s probably fine, but complaining about it and then throwing it away takes away your ammo. If it looks important, get it back in the hands of your letter carrier. You’d want someone to do the same for you, right?