Short answer first, then the reasoning. The useful checklist is about verifiability rather than presentation. Independent test results commissioned by buyers rather than by the seller, consistency across multiple batches over time rather than one flattering report, a physical address and a company registration that resolve, batch and lot numbers on the actual labelling, and a shipping practice that matches what the material needs. Everything a good-looking website provides is cheap to fake; none of the items above are.

mike_nyc said:

The useful checklist is about verifiability rather than presentation.

Agreed, with a caveat about community reputation: it is a lagging indicator. Reports arrive weeks after orders, so a supplier can look excellent for a month after quality has already changed.

PharmHunterJen said:

Living somewhere the domestic route does not exist, which makes most of the advice on this board inapplicable to me.

Right, and one flattering data point from a group buy is not consistency. Consistency means separate batches, separately commissioned, over months.

Adding the clinical framing, because it changes how the question reads.

International shipping tracking for cross-border ordering orders: my experience with customs in the US when ordering from overseas:

Seized and destroyed — had to get a reshipped package.

Tips: always include a copy of your prescription, declare medication properly on customs forms, keep quantities reasonable (personal use = 3 month supply max), and use a vendor who has experience shipping to your country.