PSA: Things You Cannot Send Via Diplomatic Post Offices

 

According to the Foreign Affairs Manual, 39 U.S.C. 413 authorizes the United States Postal Service (USPS) to establish U.S. Post Office branches at U.S. diplomatic missions abroad.  It also authorizes the Department of State to enter into an agreement with USPS to perform postal services at such branch post offices through personnel designated by the Department of State.  The Tripartite Agreement between the Department of State, Department of Defense, and USPS exercises that authority, providing a framework for the establishment and support of Diplomatic Post Offices (DPOs).
The DPO must be used only for personal mail.  Official mail, including official supplies, is not permitted in the DPO.  The mailing of dangerous goods via the DPO may present serious dangers to aircraft and passengers, and/or cause serious diplomatic concerns with host nations. 
IATA Dangerous Goods Regulations, Section 9, requires DPM (Diplomatic Pouch and Mail Division) to report to the appropriate authorities of the State when undeclared or misdeclared dangerous goods are discovered in cargo or mail.  Incidents discovered anywhere in the USPS supply chain must be reported to DPM via a Postal Offense Report in ILMS DPO.  DPM will notify the United States Postal Inspection Service (USPIS), the Bureau of Diplomatic Security (DS), and the Federal Aviation Agency (FAA).
Items known as hazardous, restricted, or perishable are prohibited for dispatch by DPO from the United States to either abroad, or from abroad to the United States, or from post to post (consult USPS Publication 52). 
See some of the restricted items below (expanded list is available via 14 FAM Exhibit 761.4 here):

Human remains are only authorized when sent via Priority Mail Express International Service (NOTE:  Express mail is not authorized to/from a DPO);

Alcoholic beverages (e.g., beer, wine, liquor, any liquid containing alcohol);

Electronic Cigarettes (e-Cigarettes).

Agriculture products (e.g., plants, seeds, bulbs, soil, fertilizer, plant food, wood chips, fruits, etc.);

Animals:  Endangered species products (e.g., lab samples, insects, etc.);

Compressed gases and aerosols (e.g., hairspray, cylinders containing residual pressure, inhalers for asthma);

Flammable liquids (e.g., nail polish and remover, hand sanitizer, lens wipes, medication containing alcohol, perfume, or cologne);

Flammable solids (e.g., safety matches);

Incendiary materials such as road flares, cigarette lighters, self-starting charcoal, MRE meals with heaters, etc.;

Items for resale (e.g., Girl Scout cookies, magazines, etc.) per 14 FAM 742.4-3;

Household Effects (HHE) or Unaccompanied Baggage (UAB) per USPS Postal Bulletin restriction N, and 14 FAM 761.4-4, Private Property in the DPO;

Firearm/ammunition/explosive devices (e.g., blanks, caps, shells, simulated ammo);

Explosives or inert training devices resembling explosives;

Firearms and objects resembling weapons or dangerous objects (e.g., air rifles, paintball guns, training weapons, weapons and/or gun parts made/fashioned by three-dimensional (3D) printers, etc.), per USPS Postal Bulletin restriction U4;

Weapons or items that resemble weapons (e.g., any spring-loaded knife (switchblade), tactical knives, fixed-bladed fighting/hunting knives, firearms, or components thereof, sling shots, bows, arrows, BB guns and pellet guns, firearms, throwing stars/spikes, ceremonial swords, toys closely resembling weapons, etc.).  NOTE:  Kitchen knives are permitted but highly discouraged; 

Per 14 FAM 310, for official supplies and equipment from the United States, the Department, the foreign affairs agencies and other U.S. Government civilian (i.e., non-DOD) agencies utilize the U.S. Despatch Agents and their Consolidated Receiving Point (CRP) Programs for shipment.
Anybody knows the restrictions for med flights?