From: JaKyL25 | #042
How do you guys get those lists anyway? Do we sell them to you or something, or are they a matter of public record somewhere, or what?
I've always wondered why some "direct marketing" goes to each and every house and some doesn't.
I think USPS gives those out, at least in a way. We got updated address-validation data & software every month, but that came from another software company. I believe they used data released by USPS to build their software. The way it worked, at least at a basic level as far as I understand, was that it had every street in the country, and a format and range of valid house numbers for those streets. Like if you were looking at Park Ave in New York, it might have the addresses valid from 10 through 950 (or whatever it is, I just made those numbers up). So if you checked if 379 Park Ave was a valid address, it would tell you it was because it was within the accepted range. There might be some streets where a number gets skipped, like there's a #13 next to a #17 with no #15 in between, which would turn up as valid even though there was no physical building, but my guess is that most companies find it cheaper to just mail those out anyway rather than trying to track them down. Maybe they keep track of their own list of ones to skip if they get undeliverable mail returned to them? Or maybe they just keep sending it out.
Then there's another service, I think it was called DPV (Delivery Point Verification) which I think actually had a list of every deliverable address in the country. It used to be extra but around two years ago it became mandatory for all presorted bulk rate mail. This one could tell you if an address really existed besides just whether it was in the valid range. I'm not sure if it dealt with apartment numbers or not, but I think it may have.
Armed with this data, it would be pretty trivial to generate a list of all addresses even if you couldn't just get it straight out of the software's data files which you probably could.
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Black Turtle spilled my diet soda!