M : (overprint on stamps of Belgium) Military parcel posts.
M. : Spanish - Madrid or Manresa.
M. : Venetian - Montebelluno (1732/1734).
M. : Italian - Milano or Montebelluno.
M. : Swiss - Morgen (Morning) (1839).
M. : Belgian - (in two circle) Malines (1787).
M. : Belgian - Menin (1760/1800).
M. : Canadian - Montreal (1774).
M. : Dutch - (fancy type in circle) Middelburg (1763/1789).
M. : Dutch Indies - Madassar.
M. : Irish - (preceded by abbreviated month and date) Morning (1774/1809).
M. : (overprint on stamps of South Australia) Officials (1868/1874) Military.
M.A. : (overprint on stamps of Argentina) Officials - Ministry of Agriculture.
MADAGASCAR : (overprint on stamps of France) Madagascar (1895).
MADEIRA : (overprint on stamps of Portugal) Madeira (1868/1898).
MADERANERTHAL : Switzerland - Hotel local stamp.
MAFEKING : (overprint on stamps of Bechuanaland) Cape of Good Hope (1900).
MAFEKING : (overprint on stamps of Cape of Good Hope) 1900.
MAGAZON A MOROC : Sultanate of Morocco - Local issue of questionable repute (1891) - Mazagan to Morocco.
MAGAZON MARAKECH : Sultanate of Morocco - Local issue of questionable repute (1893) - Mazagan to Marakesh.
MAGYAR KIR(ALYN) POSTA : Hungary - Hungarian Royal Post.
MAGYAR KIR. HIRLAP BELYEG : Hungary - Newspaper tax stamps.
MAGYAR NEMZETI KORMANY SZEGED : (overprint on stamps of Hungary) Szeged - Serbian occupation (1919) - Hungarian People's Government Szeged.
MAGYAR NEPKOZTARSASAG : Hungary (1919) - People's Popular Republic.
MAGYAR TANACS KOZTARSASAG : Hungary (1919) - Hungarian Soviet Republic.
MAGYARRORSZAG : Hungary (1925) - Hungarian State.
MAHRA SULTANATE OF QISHN AND SOCOTRA : South Arabia (1967).
MAI GT. PRE. 1902 : (overprint on stamps of Haiti): (1902) - Gouvernement Provisoire (Provisional Government).
M.A.L. : Cancel of British Forces in North and East Africa - Military Authority Lira.
MALACCA : Malaya - Malacca.
MALAGA : (overprint on stamps of Spain) Revolutionary issues - Malaga (1937).
MALAGA ARRIBA ESPANA : (overprint on stamps of Spain - Malaga) Revenues.
MALAYA : (overprint over portrait of Sultan) Malaya - Kelantan, Negri Sembilan, Pahang, Perak, Perlis, Selanegor or Trengganu.
MALAYA : (overprint over picture of mosque) Selangor.
MALAYA : (overprint over picture of over picture of State Arms) Negri Sembilan.
MALAYA BORNEO EXHIBITION : (overprint on various stamps of Malayan States).
MALAYA PERLIS : Malaya - Perlis.
MALAYA POSTAL UNION : Malaya - Postage dues (1945).
MALDIVES : (overprint on stamps of Ceylon) Maldives Islands (1906/1909).
MALMEDY : (overprint on stamps of Belgium) Germany - Belgian occupation of Melmedy (1920/1921).
MALUKA SELATAN : South Moloccas (Indonesian private issues).
MANAMA : Ajman - Manama.
MANDAT : Netherlands - Money order stamps (1894).
MANIZALES : Colombia - Manizales.
MAPKA : Russia, Finland or Serbia.
MARCA DA BOLLO : Italy.
MARIANAS ESPANOL : (overprint on stamps of Spain) Mariana Islands (1899).
MARIANEN : Mariana Islands (1899/1919).
MARIENWERDER : (overprint on stamps of Germany) Marienwerder plebescite (1920).
MAROC : French Morocco - Morocco.
MAROCCO : (overprint on stamps of Germany) Germany - Offices in Morocco.
MAROKKO : (overprint on stamps of Germany) Germany - Offices in Morocco (1911).
MARRUECOS : (overprint on stamps of Spain) Spanish Morocco.
MARRUECOS ESPANOL : Spanish Morocco - Northern Zone.
MARSCHELL INSELN : Marshall Islands.
MARTINIQUE : (overprint on stamps of French Colonies) Martinique (1886/1892).
MAT TUAN D.T.G.P. MIEN NAM VIET NAM : National Front for the liberation of South Vietnam.
MAZATLAN : (overprinton stamps of Mexico - Mazatlan) Mexico - Mazatlan (1916).
M.B. : British - Mangrove Bay (Bermuda) (1865).
M. B. : (overprint on stamps of South Australia) Officials (1868/1874) Marine Board.
M.B.D. : British - Moveable Box (1844/1939).
MBLEDHJA KUSHTETUGESE : (overprint on stamps of Italy) Albania - Italian dominion (1939).
MBRETNIJA SHQIPTARE : Albania - Italian occupation.
MBR SHQITARE : Albania - air post.
M.D.G.A. : Prussian - Ministerium der Geistlichen Angelegenheiten - Disinfection mark on cholera letters.
MECKLENB. : German States - Mecklenburg-Schwerin (1856/1867).
MEDELLIN PROVISIONAL : Colombia - Antioquia (1888/1889).
MEDIA ONZA : Spain - Official stamps (1854/1863).
M.E.F. : British - Mesopotamian Expeditionary Force (1914/1918 War).
M.E.F. : (overprint on stamp of Italian East Africa) - Middle East Forces (1942/1952).
M.E.F. : (overprint on stamps of Great Britain) Great Britain - Offices in Africa (1942/1950) - Middle East Forces.
MELAKA : Malaysia - Malacca.
MELAT-I-KAZERUN 1335 : (overprint on stamps of Iran) Unofficial rebellion overprint (1917).
MEMEL : (overprint on stamps of France) Memel (1920/1923).
MEMEL GEBIET : Memel - Memel District.
MEMEL with KLAIPEDA : Memel - Lithuanian occupation (1923).
MENSAJERIAS : Uruguay - Special delivery stamps.
MET. : Austrian - Metkovich.
METELIN : (overprint on stamps of Russia) Russia - Offices in Turkey (1910).
MEXICO TRANSITORIO : Mexico - Sonora revenues.
M.G. : (overprint on stamps of Argentina) Officials - Ministry of War.
M.H. : (overprint on stamps of Argentina) Officials - Ministry of Finance.
M & I. : French - (oblong frame) Maurice et Indies (Mauritius and the Indies) (1835).
M.I. : (overprint on stamps of Argentina ) Officials - Ministry of Interior.
MIL : Italian - Milano.
MILAN/F : French - Two separate stamps used at the French P.O. in Milan - Meaning of F unknow (1779).
MILAN/L : French - Two separate stamps used at the French P.O. in Milan - Meaning of L Lombardo (1779).
MILANO/LF : French - Milan Lettre Francaise.
MILIT. (POST) PORTOMARKE : Bosnia and Herzegovina - Military post postage dues.
MILITAR K.u.K. POST : Bosnia and Herzegovina - Austrian Administration (1912).
MILITARPOST : Bosnia and Herzegovina.
MILITAR POST EILMARKE : Bosnia and Herzegovina - Special handling stamps.
MILL. : (currency surcharge on stamps of France) France - Offices in Egypt (1921/1928).
MILLIEME(S) : (currency surcharge on stamps of France) France - Offices in Egypt (1921/1928).
MILO : Italian - Milano.
M.J.I. : (overprint on stamps of Argentina) Officials - Ministry of Justice and Education.
M. KIR. : Hungary (1916).
MM : Italian - (monogram) Milan (1764/1793).
M.M. : (overprint on stamps of Argentina) Officials - Ministry of Marine.
MOGADORO A MAROC : Sultanate of Morocco - Local issue of questionable repute (1895) - Mogadoro to Morocco).
Mogy M.M. : Brazilian - Mogy Mirim.
MOHГOЛ ЩЧAAH : Outer Mongolia.
Mon. B. : French - Maison Bicêtre (Prison) (1798/1900).
MONGTSEU : (overprint on stamps of Indo-China) France - Offices in China - Mongtseu (1903/1909).
MONGTZE : (overprint on stamps of Indo-China) France - Offices in China - Mongtseu (1903/1909).
MONISTIR : (overprint on stamps of Turkey) Turkey - For royal visit of Sultan to Rumelia (1911) - City of Monistir.
MONSTER : (overprint on stamps of Dutch) Dutch language countries - Specimen.
MONT ATHOS : (overprint on stamps of Russia) Russia - Offices in Turkey - Mont Athos (1909/1910).
MONTE CASSINO 1944 : (overprint on stamps of Poland - Exile in Great Britain) Polish government in exile (1944).
MONTENEGRO : (overprint on stamps of Austria) Montenegro - Austrian occupation (1917/1918).
MONTENEGRO : (overprint on stamps of Italy) Montenegro - Italian occupation (1941/1942).
MONTEREY : (overprint on stamps of Mexico - Monterey) Mexico - Monterey.
MONTEVIDEO : Uruguay - Montevideo (1858/1867).
MONTSERRAT : (overprint on stamps of Antigua) Montserrat (1876).
M.O.P. : (overprint on stamps of Argentina) Officials - Ministry of Public Works.
MOQEA : (overprint on stamps of Peru - Moquegua - Chilean) Peru - Moquegua - Chilean occupation (1885).
MOQUEGUA : (overprint on stamps of Peru - Moquegua) Applied after regional earthquake (1881).
MOQUEGUA : (overprint on stamps of Arequipa) Peru - Arequipa - Moquegua - Chilean occupation (1885).
MORELIA : (overprint on stamps of Mexico - Morelia) Mexico - Morelia.
MOROCCO AGENCIES : (overprint on stamps of Gibraltar) Great Britain - Offices in Morocco.
MOROCCO AGENCIES : (overprint on stamps of Great Britain) Great Britain - Offices in Morocco.
MORVI : India - Morvi (1931/1948).
MOULINS B. : French - Moulins Bourbonnais (1781/1791).
MOYEN CONGO : Middle Congo.
M.P.O. : Egyptian - Military Post Office.
MQE : (overprint on stamps of French Colonies) Martinique (1886/1891).
M.R. : (overprint on stamps of South Australia) Officials (1868/1874) - Manager of Railways.
M.R. : French - Maison du Roi (Royal Household) (1838/1847).
M.R.C. : (overprint on stamps of Argentina) Officials - Ministry of Foreign Affairs and Religion.
M. R. G. : (overprint on stamps of South Australia) Officials (1868/1874) - Main Roads Gambierton.
M.S. : German - Mecklenburg-Schwerin.
M-S : British - Mis-sort (1826).
M.S.G.A. : Italian - Marchese San Giacinto Amministratore (della Posta Naples) is the verification of the postage due (1830/1835).
Mü. : Prussian - Mühlhausen.
MUESTRA : (overprint on stamps of Spanish) Spanish language countries - Specimen.
MULTA : Several countries - Postage dues - Fined.
MULTADA : Chile - Postage dues- Fined.
MULTAS : Ecuador - Postage dues - Fined.
MUSCAT & OMAN : Oman (1966/1970).
MUSTER : (overprint on stamps of German) German language countries - Specimen.
M.V.i.R. : (overprint on stamps of Romania - German) Romania - German occupation (1917/1918) - Militar Verwaltung in Rumanien (Military Administration of Romania)).