Cosa Nostra Dead Drops

Good operational security is hard, and often uses manual technologies:

Investigators described how Messina Denaro, 53, disdains telecommunications and relies on handwritten notes, or "pizzini,'" to relay orders. The notes were wadded tight, covered in tape and hidden under rocks or dug into soil until go-betweens retrieved them. The messages were ordered destroyed after being read.

That's a classic dead drop.