It is the AddressesV3 service. We're planning on using it (for the website redesign) to make sure that the addresses are correct (enough). There's a significant number of people who register and quit/get fired, yet still have to make one final filing (for a state government agency) that we snail-mail them a final "I'm done with this" paper form to fill out. And every couple of years an envelope gets returned as "undeliverable".

https://developers.usps.com/addressesv3

For bulk shippers the USPS will penalize you if you have... well it was not bad addresses but non-standard addresses. The mail order company I worked for a few years ago put more effort than I expected to normalize and verify addresses met USPS standards. So I guess the penalty made it worth it.

Yeah so does Australia Post. I've dug too deeply but Google Maps on face value seems to provide it as well.