Among the things that cannot be mailed at all:
- Commercial tags of metal.
- Altered or renovated butter. (you know, honey, I'm feeling antsy. I think it's time to renovate our butter.)
- Perishable infectious biological substances.
- Perishable noninfectious biological substances. (well, that about covers it.)
- Radioactive materials.
- Shipments bearing caution labels indicating the contents are flammable. (flammable materials are okay as long as they don't have labels)
- Used or secondhand hives or bee supplies. (there goes my idea for BeeBay, your transborder source for secondhand hives)
Banknotes valued at $100 or more must be put up in a compact package and securely tied with strong twine before wrapping. The wrapper must be linen or other strong, woven material, linen lined paper, or two thicknesses of strong kraft paper. After wrapping, the package must be again securely tied or stitched and sealed at the points of closing. (they fail to mention that the package must be decorated with origami cranes)
The following must not be accepted for insurance:
Bees, postage stamps (canceled and uncanceled) and albums in which they are mounted, and parcel post packages addressed to CFPOs. (bees can't be insured? But think of the children! they have larvae to support!)