Transit times by route, from a logged dataset posts 31–39

Customs holds: if a parcel is held at customs and you can contact customs directly, declaring your personal use and providing documentation (order, labelling) can help. Most customs officials are reasonable when they know what they are dealing with.

Coming back to post #30, because the follow-up matters more than the original answer.

Import restrictions by jurisdiction: what is legal to import for personal use varies enormously by country. Some jurisdictions are quite permissive; others are not. Checking your own country's rules before ordering is prudent.

post #32 answers the question as asked. The question underneath it is different.

For anyone arriving from a search: the marked solution above is the direct answer, and the replies underneath it add the caveats that make it safe to use.

Tracking stops updating: tracking last updated days ago usually means the package is in transit and will not update until it reaches the next scanning point. No update for weeks means it might be stuck.

Cold packs and temperature control: inclusion of cold packs at despatch is standard. Whether they maintain temperature through transit depends on journey duration and ambient temperature. Long journeys through warm climates put product at risk.

Two things before anyone answers the substance.

First, the context in the first post is clear and specific. Second, the question is framed so that an answer can actually address it. Both are the norm here and both matter more than they sound.

post #36 is right about the mechanism and I think understates the practical bit.

Declaring contents accurately: declaring accurately reduces intervention risk. A declaration of "peptide research chemical, 5 grams" is better than "vitamin" or "other" because custom officials can verify a declared chemical is actually what was declared.

Worth separating two things that post #34 runs together.

Documentation after arrival: photograph the parcel and its contents on arrival. If something later turns out wrong (damage, loss, wrong item) you have evidence of the condition it arrived in.

Picking up post #36: that is the part I would want checked first.

Insurance and carrier liability: most parcel carriers limit liability. Understanding the limits before choosing a carrier matters if you are shipping expensive material.