The free mailing privilege only applies to military service personnel and designated civilians in specially designated areas with limited Postal support. In other words, it is only free for those deployed personnel mailing from designated overseas locations identified by The Department of Defense (DoD).  This program is not for their loved ones, family, or friends back home mailing mail to them. Regular Domestic postage is used when mailing overseas to military personnel.  There are no discounts for mailing from the U.S. to overseas APO and FPO locations.  The free mailing privilege may only be used by members of the U.S. Armed Forces on active duty who are:

Assigned to military duty in certain overseas areas, and who mail the matter at an Armed Forces Post Office™ in that area. -OR-  Hospitalized in a facility under the jurisdiction of the Armed Forces due to disease or injury incurred as a result of service in these designated areas.  Note: The "free" mail privilege is only for military personnel sending mail home to the USA.  Authorized Locations:

"Operation Enduring Freedom"

Aboard ships in the Persian Gulf
Aboard ships in the Red Sea
Aboard ships in the Gulf of Oman
Aboard ships in the North Arabian Sea
Aboard ships in the Gulf of Aden
The total land areas of Afghanistan, Bahrain, Diego Garcia, Djibouti, Ethiopia, Jordan, Kazakhstan, Kurdistan, Kuwait, Oman, Pakistan, Qatar, Saudi Arabia, Tajikistan, United Arab Emirates, Uzbekistan, and Yemen.

"Operation Freedom Eagle"

All of the islands of the Republic of Philippines south of the island of Luzon within the following described limits: 08-00N/116-30E; 04-45N/119-30E; 05-00N/128-00E; 13-00N/129-00E; 12-30N/116-00E.

"Operation Iraqi Freedom"

The total land areas of: Iraq, Bulgaria (mail originating from APO 09312), Crete, Cyprus, Romania (mail originating from APO 09338), Turkey (east of 35 degrees east longitude) - Expired November 10, 2003. Exception : Iraq still qualifies for free mail privileges.

"Operation Joint Forge / Joint Guardian"

Aboard ships in the Adriatic Sea
Aboard ships in the Ionian Sea north of the 39th parallel
The total land areas of Albania, Hungary, and the Former Republic of Yugoslavia (including: Bosnia-Herzegovina, Croatia, Zagreb, Macedonia, Serbia-Montenegro, Kosovo, Vojvodina, Slovenia.