text: Provide Human Resources Services
  BATTLEFIELD FLOW
  4-73. During LSCO, the combatant commander determines mail flow priorities based on METT-TC. Prior
  to deployment, the ASCC G-1/AG determines the initial postal support requirements in coordination with
  the combatant commands, other Service components, and the supporting TSC TPOC. In determining the
  requirements, the ASCC G-1/AG considers the infrastructure in the AO, deployment timing, force
  composition, and expected deployment duration. Through operational analysis and with input from the TSC,
  the ASCC determines what postal unit structure is necessary to support the operation and where to place the
  MMT within the AO. The normal postal unit requirement for supporting a deployed force is one MMT per
  inter-theater APOD receiving bulk mail, a postal platoon providing postal finance services support for up to
  6,000 Soldiers and DOD and DA Civilians, and a HR company for every three to seven postal platoons.
  Depending on the scope and expected duration of an operation, postal platoons and/or HR companies deploy
  with the main body of the operational Army. A trained and fully equipped postal unit requires a minimum of
  48 hours to establish postal operations. Postal units must be established before the movement of mail in or
  out of the AO. All METT-TC considerations must be addressed.
  4-74. The USPS sorts mail based on their physical plant capacities and works with DOD to provide sortation
  to ZIP Codes and more specifically to geographic areas or major cluster of military personnel, and not
  necessarily tied to a unit. To support force deployment, the MPSA, in coordination with the USPS,
  operational combatant commands, and Service component commands, assigns ZIP Codes to forces after
  requirements have been met (for example, postal personnel and equipment, logistics transportation, and
  host-nation agreement concerns); these requirements are processed through the Automated Military Postal
  System. The ZIP Code may be provided to a unit before deployment, but only if all the prerequisites for that
  ZIP Code have been met. The MPSA also coordinates with the JMPA for mail transportation from CONUS
  to the JOA. During operations, intra/inter-theater mail may be transported by commercial, contract, or
  military ground, sea, rail, and air transportation segments.
  4-75. Upon notification from MPSA, the USPS sorts and packages mail, in time of war or emergency, as
  determined by the Secretary of Defense. The postal service agrees to––
  * Allow the DOD to control ZIP Code assignment to all military units.
  * Specify jointly with the MPSA the sorting of mail for overseas forces.
  4-76. The HR company and subordinate postal platoons located at the MMT receive the mail and distribute
  it to HR companies supporting subordinate corps and division units, or postal platoons supporting subordinate
  brigades. The postal platoon(s) receives mail dispatched from the MMT, sorts it by supported units, and
  prepares it for dispatch to designated mail delivery points. Company and battalion mail clerks pick-up mail
  from the mail delivery point and coordinate delivery to addressees. Mail clerks coordinate collection of
  retrograde mail from unit Soldiers and deliver it daily to the mail delivery point at the same time as pick-up
  of unit mail. The same transportation used to deliver mail to delivery points transports retrograde mail, to
  include casualty mail, in reverse through the postal network. Figure 4-1 on page 4-18 depicts the mail flow
  from CONUS to unit/Soldier. See ATP 1-0.2 for further information regarding mail flow.