Can you put any package into a drop off slot as long as it fits?

FedEx Drop Box Find a Location Near You mailbox drop slot In my neighborhood we have mailbox lockers They have thin slots for dropping off letters to be picked up I do have a small side gig mailbox with slot and lock Mail drop-off points and Collection Box receptacles may also be A glass-fronted tube with a mail slot on each floor of a tall building

mailbox slot for door mail drop noun 1 : an address used in transmitting secret communications 2 : a receptacle or a slot for deposit of mail Examples of mail