901 selected
- Siam (Thailand)
- Siam - British Post Office [Bangkok]
- Sierra Leone
- Singapore
- Sleswick
- Slovakia
- Slovenia
- Solomon Islands
- Somali Coast - French Protectorate (Côte Française des Somalis)
- Somalia
- Somalia - Illegal Stamps
- Somalia - Puntland - Illegal Stamps
- Somaliland - British Protectorate
- South Africa
- South Australia
- South Georgia and the South Sandwich Islands
- South Kasai
- South Korea
- South Maluku - Cinderella (Maluku Selatan)
- South Sudan
- South Yemen [1967-1990] (People's Democratic Republic of Yemen - PDR)
- South-West Africa
- Southern Nigeria
- Southern Rhodesia
- Sovereign Military Order of Malta
- Soviet Union
- Spain
- Spain - Cinderella
- Spain - Local issues
- Spanish Guinea
- Spanish Sahara
- Spanish West Africa
- Spanish West Indies
- Sri Lanka (Ceylon)
- Stellaland
- Straits Settlements
- Sudan
- Suez Canal
- Suriname
- Swaziland (Eswatini)
- Sweden
- Sweden - Isö - Cinderella
- Sweden - Jul stamps
- Switzerland
- Switzerland - Cinderella
- Switzerland - Swiss Post abroad
- Syria
- Tahiti
- Taiwan
- Tajikistan
- Tajikistan - Illegal Stamps
- Tanganyika
- Tanger - Franse post
- Tangier - British post office
- Tangier - Cinderella
- Tangier - Spanish post office
- Tanzania
- Tanzania - Illegal Stamps
- Tasmania
- Téte
- Thailand (Siam)
- Thrace
- Thule
- Thurn und Taxis
- Tibet
- Timor - Oecusse - Cinderella
- Tobago
- Togo
- Tokelau
- Tonga
- Transcaucasia
- Transkei
- Transnistria
- Transvaal
- Triest - Venezia Giulia
- Triest - Zone A
- Triest - Zone B
- Trinidad and Tobago
- Tristan da Cunha
- Tunisia
- Turkey (Türkiye)
- Türkiye (Turkey)
- Turkmenistan
- Turkmenistan - Illegal Stamps
- Turks and Caicos Islands
- Turks and Caicos Islands - Caicos
- Tuva
- Tuva - Illegal Stamps
- Tuvalu
- Tuvalu - Funafuti
- Tuvalu - Nanumaga
- Tuvalu - Nanumea
- Tuvalu - Niutao
- Tuvalu - Nui
- Tuvalu - Nukufetau
- Tuvalu - Nukulaelae
- Tuvalu - Vaitupu
- Uganda
- Ukraine
- Ukraine - Cinderella
- Umm al-Qaiwain
- United Arab Emirates
- United Arab Emirates - Trucial States
- United Nations - Geneva
- United Nations - New York
- United Nations - Vienna
- United States - Confederate States
- United States of America (USA)
- United States Virgin Islands - Cinderella
- Upper Senegal and Niger
- Upper Silesia
- Upper Volta
- Upper Yafa
- Uruguay
- USA (United States of America)
- Uzbekistan
- Uzbekistan - Karakalpakstan - Illegal Stamps
- Vanuatu
- Vathy
- Vatican City
- Venda
- Venezuela
- Victoria
- Vietnam
- Vietnam - North Vietnam
- Vietnam - South Vietnam
- Vietnam [1945-1953] - Democratic Republic
- Vietnam [1963-1976] - Viet Cong
- Vietnam[1951-1954] - State of Vietnam
- Wallis and Futuna
- West Ukraine
- Western Australia
- Western Sahara - Illegal Stamps
- Württemberg
- Württemberg - French zone
- Y.A.R. (Yemen [1962-1990] - Arab Republic)
- Yemen - Kingdom [1962-1970]
- Yemen - Republic
- Yemen [1918-1962] - Kingdom
- Yemen [1962-1990] - Arab Republic (Y.A.R.)
- Yugoslavia
- Yugoslavia - Cinderella
- Yugoslavia - Istria
- Zaïre (Congo-Kinshasa)
- Zambezia
- Zambia
- Zanzibar
- Zanzibar - French post offices
- Zimbabwe
- Zululand
- [Unspecified]
- Not filled in