Payment by the Postal Service of the full amount claimed or acceptance by the claimant, his agent, or legal representative, of any award, compromise, or settlement made pursuant to the provisions of the Federal Tort Claims Act, shall be final and conclusive on the claimant, his agent, or legal representative, and any other person on whose behalf or for whose benefit the claim has been presented, and shall constitute a complete release of any claim against the United States and against any employee of the Government whose act or omission gave rise to the claim by reason of the same subject matter.