The US Postal Service is warning us that if the proper country-code abbreviation is not used when sending mail to European countries, mail will be returned or delayed.

Austria - A
Belgium - B
Bulgaria - BG
Croatia - CRO
Czech Republic - CS
Cyprus - CY
Denmark - DK
England - UK
Estonia - EE
Faeroe Islands - FR
Finland - FIN
France - F
Germany - D
Greece - GR
Hungary - H
Iceland - IS
Israel - IL
Italy (including San Marino and Vatican City) - I
Latvia - LV
Liechtenstein - FL
Lithuania - LT
Luxembourg - L
Malta - MSD
Moldava - MD
Monaco - MC
Netherlands - NL
Norway - N
Poland - PL
Portugal - P
Romania - RO
Russia - CSI
Slovakia - SK
Slovenia - SL
Spain (including Canary Islands) - ES
Sweden - S
Switzerland - CH
Turkey - TR
United States of America - US
Yugoslavia (including Serbis & Montenegro) - YU