Related Rule
New Zealand
Practice Relating to Rule 125. Correspondence of Persons Deprived of Their Liberty
New Zealand’s Military Manual (1992) provides:
Immediately upon capture and upon transfer from one place of detention to another, prisoners shall be allowed to send a card to their families and to the Central Prisoners of War Agency giving information of their capture, address and state of health. They shall be allowed to send and receive letters and cards and, in exceptional circumstances, telegrams as well. 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, § 929.
The manual further states:
All persons in the territory of the belligerent or in territory occupied by him must be enabled to transmit to, and receive from, members of their families, wherever they may be, news of a strictly personal nature. 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, § 1113.
The manual also states:
As soon as he is interned, transferred, or becomes sick, the internee is entitled to send a card to his family and to the Central Information Agency indicating his present location and his state of health. An internee is allowed to correspond frequently but letters may be limited in number, if the Detaining Power finds it necessary, and are subject to its censorship. 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, § 1127.
Lastly, the manual specifies that in non-international armed conflicts, detained and interned persons “shall be allowed to send and receive letters and cards”. 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, § 1814(3).