Related Rule
Argentina
Practice Relating to Rule 125. Correspondence of Persons Deprived of Their Liberty
Argentina’s Law of War Manual (1969) reproduces Article 71 of the 1949 Geneva Convention III and Article 25 of the 1949 Geneva Convention IV. 
Argentina, Leyes de Guerra, RC-46-1, Público, II Edición 1969, Ejército Argentino, Edición original aprobado por el Comandante en Jefe del Ejército, 9 May 1967, §§ 2.066 and 4.008.
Argentina’s Law of War Manual (1989), referring to Articles 71, 72, 74, 75 and 76 of the 1949 Geneva Convention III, provides: “Prisoners of war shall be allowed to send and receive letters and cards.” 
Argentina, Leyes de Guerra, PC-08-01, Público, Edición 1989, Estado Mayor Conjunto de las Fuerzas Armadas, aprobado por Resolución No. 489/89 del Ministerio de Defensa, 23 April 1990, § 3.16.
The manual also provides that internees shall be enabled “to give news of a strictly personal nature to members of their families, wherever they may be, and to receive news from them”. 
Argentina, Leyes de Guerra, PC-08-01, Público, Edición 1989, Estado Mayor Conjunto de las Fuerzas Armadas, aprobado por Resolución No. 489/89 del Ministerio de Defensa, 23 April 1990, § 4.14.