(2) A claim submitted to a Foreign Service Office or any other agency or subdivision of the U.S. Government shall be forwarded to the Office and considered filed as of the date it was received at the Foreign Service Office or other governmental agency or unit.
(b) A claim submitted by mail shall be considered filed as of the date of delivery unless a loss or impairment of benefit rights would result, in which case a claim shall be considered filed as of the date of its postmark. In the absence of a legible postmark, other evidence may be used to establish the mailing date.