Online Shipping Labels can you just put package in any mailbox?

Ok so Im mailing out some cards today and I want to try using the online shipping label method since Delivery Confirmation is only 10 cents. Im wondering if I print the label and put it on the small top loader envelope with prepaid postage can I just stick that in any mailbox or do I still need to give it to someone behind the post office desk?

you have to put a label on each individual item, but as far as i know, yes you can put it in any mailbox. you’ve already paid for the postage (online) so there’s no need to go to the post office.