Signature required after USPS policy change?
Honestly, that "may require signature" line has been around forever. It's pretty much just boilerplate USPS slaps on anything with insurance. I've been seeing it on tracking updates for at least a year now—even on packages that end up getting tossed in the mailbox without anyone signing. It's not really enforced. More of a CYA move on their end.
Most of the time, if the seller uses a standard stealth letter—plain bubble mailer, no obvious markings, addressed to a real person—the carrier just drops it in the box or at the door. I've had letters go through with zero issues even when tracking said signature was required. The only time I actually had to sign was when the package was Priority Mail Express and the insurance value was high enough to trigger a real delivery confirmation. Even then, the carrier just left a notice and I picked it up at the post office. But that's rare for a typical stealth letter.
As for transit hubs, most of these letters go through the standard USPS network—regional distribution centers like the one in Jersey or Dallas. I've noticed envelopes tend to get delayed more if they hit a major sorting facility over a weekend or holiday. Packaging is usually fine as long as it's not too bulky. A standard #10 envelope or a thin bubble mailer holds up well, but if you try to squeeze in a thick ID, it might get caught in the machines and arrive a little crumpled. Custom side: for domestic shipments, there's no customs involvement, obviously. If you're ordering from overseas, that's a whole different ballgame where signature might actually be enforced.
Speed-wise, USPS First Class is still the go-to for most stealth letters—usually 2–5 days within the continental US. Priority gets there a day faster but costs more and doesn't really change the signature situation. Overall, I wouldn't sweat the "may require signature" line. It's generic. Unless the vendor explicitly pays for signature confirmation, your letter will almost certainly just get left in the box.