There doesn't seem to be much information about how to do this with USPS though.

Pet, ESA, or legitimate service animal, it doesn't matter.

You need his rank, time in service (you can even guess really, doesn’t vary a ton), and zip code.

Doesn’t sound like this was the case.  

Thank you.The general rule I go by, after flipping a ton of houses, is that I regret selling them now.If you buy them right (we’re an exception, as we buy at 7 to 15 cents on the dollar) and rehab them properly, you’ll get a ridiculous profit by keeping them, using strategies like the BRRRR method.Honestly, it doesn’t make much sense to sell them right away if you bought them right.

@Alex Scattareggia, the withholding tax, as you suggested, doesn't have to be an issue providing that your property is profitable enough.

I have a ninja trick (that sounds cool doesn't it) to where the bank will accept alot less than the appraised value.

Even google doesn’t have a street view of the house, so I need to be conservative here.Do I have any leverage in this situation?

This doesn’t make it a bad deal, it just means giving up something for a  different benefit.  

The most likely scenario is that you refuse to pay him, or make him an offer he doesn’t accept, and he files a mechanics lien on the property.