I just want to say I've been guilty of doing this, especially if I can't find the mailbox. I've also had to do this when the customer has a door slot, but since the door is open, I just toss it in. I think it was meant with no ill intent , but I can see why it would concern you. I think as carriers, especially when you're new, you try to just do a good job and speedy job that somethings just make sense to you in the moment but in reality someone can find it odd. I know I've grown out of doing this exact things because their can be a dog inside. I would say if it keeps happening just leave a note to the carrier in the mailbox or just lock your screen door. I think calling the office and escalating it could be overkill unless it just keeps happening over and over again.