Some US researchers did a series of postal experiments and published the results online. They mailed various packages via the US postal service to see if they were received and how long they took to arrive. They purposefully didn’t wrap items and chose very heavy, strangely shaped, suspicious, seemingly sentimental and even disgusting items. The results are interesting and hilarious.
In once case they wrapped and posted a brick. It arrived as a “plastic bag containing broken and pulverized remnants of brick. Inside was a small piece of paper with a number code on it.”. They also posted a small bottle of spring water, which they observed the postman open and drink during his round.