Yes to both. (And, in this case, it was the US mail carrier who left the notice in the mail.)
Essentially, yes. About the only exception is if you put a letter or something (with proper postage, of course) in there for the mailman to pick up.
That kind of fake notice is regularly sent to recipients who didn’t order anything, in the hope that the ignorant will click on the link and get infected with a virus or some phishing software. I get several of those weekly, all of them – I say again, ALL of them – are bogus. If you didn’t order anything, or the notice doesn’t specify enough to verify it (product, shipper, etc.), ignore it.
Amazon itself is full of scams. Item ratings are sometimes full of fake reviews, especially the 5 star reviews. You can sometimes tell, like if the wording is slightly off or if the review is sufficiently vague. Also if lots of people aren’t confirmed buyers or new accounts. There are websites that let you scan the reviews for potential fakes (keep in mind false positives too, though; bad reviews don’t necessarily mean bad product). Two of these websites are ReviewMeta and FakeSpot.
UPS and Fedex attach a self-adhesive tag to the door. USPS is the only other people who can access my mailbox. Individual keys work on your box, while they have a master key which essentially takes the entire frame off the mailboxes.
Amazon sat on one of my packages for two weeks earlier this month. I actually had to call their super-secret customer service line to complain.
PS Amazon did not allow me to leave a review on this item because I was not a confirmed buyer. Odd!
Did you, tho? If they shipped from China, that means they were fulfilled by the seller. I was under the impression that “Fullfilled by Amazon” meant that while the item was from a third-party seller, it was already sitting in an Amazon warehouse, stateside, ready to be packed and shipped.
https://www.amazon.com/gp/help/customer/display.html?nodeId=106096011
This thread is already full of a ton of incorrect information. Let’s not continue to lead people astray by falsely equating “Fulfilled by Amazon” with “Shipped directly from China” (which is a real thing, which you experienced).
Amazon does get very confusing.
I understand they are trying to offer a wide selection, but it’s very hard sometimes to keep up with who is selling the product.
Especially when a product is offered by several companies, there will be multiple listings. I try to always pick Amazon if possible.
So, were the cushions attractive and comfy as advertised?
It’s frustrating waiting for an update.
Perhaps you should start treating posters just like eBay! 
It’s actually worse than that. For the same product, seller inventory is commingled. So if Good Co and Fraud Co are both selling iPhones, in the Amazon warehouse the inventory they supply is combined together. If you buy something from Good Co, you might actually get a product supplied by Fraud Co.
Eh, I had an order from China fall through once, too. I think it was just a usb stick, though. So I didn’t report it to Amazon. I guess just be aware and don’t buy from that seller again.
Fyi, you’re original statement about local delivery companies is correct.
Two of the newer programs for delivery are:
1 - Local small delivery companies
You need at least a van and a uniform of some kind, but in general the bar is pretty low
2 - Average Joe/Jane person
You need at least a pulse and a car, the bar is really low
You sign up, you choose when and how long you want to work
You go to a facility, pick up some packages and you deliver them
This was my understanding as well. If an item is “Fulfilled by Amazon”, it shouldn’t be coming from overseas.
These *4 seat cushions have logged more air miles than I have. 
The tracking info has a couple references to places in China. I’ve never flown outside the continental states.
I think my mom will love them. I like the deep brown. Still in package but I gave them a squeeze. Very springy foam.
*2 per pack
I never knew that, thanks! Now I can’t decide if I like the system or not. On the one hand, no mass advertising just stuffed into every letterbox; on the other, things may end up in nonobvious locations…
The only mass advertising comes from sellers who pay special postage rates for the privilege of having the post office stuff their material into every letterbox. 
You’re mixing up who the seller is (Amazon vs. some third party), which doesn’t really matter, with who the fulfiller is, which really matters a lot. I recommend you do what I do - prefer stuff fulfilled by Amazon and is labeled ‘Instock.’ If it’s fulfilled by a third-party or out-of-stock, assume you won’t see it for two weeks at least and act accordingly.
I’ll start looking closely who fullfills the order.
You’re right. I was getting mixed up.
So, to summarize:
Nothing has changed in the way Amazon ships things.
Nothing has changed in the way they disclose who is selling & shipping any item you buy, which has always been clearly shown on the product page and again on the order confirmation page.
This was not a “Fulfilled by Amazon” item.
You got good prompt service from a Chinese vendor shipping from China.
China Post is the Chinese national carrier.
Am I missing anything?