on 08-27-2023 03:59 PM
You don't have to drop it off at the Post Office, but it is a good idea to do so... as you will get it scanned immediately and a receipt that shows that you have actually done so.
Dropping in a mail box does not give you any proof that you have actually mailed it until the first scan (if that ever happens, you item can go 'missing' from the mail box to the sorting center and never gets scanned).