The bill passed on a 62-37 vote.
Under the measure, the postal service would get an $11 billion refund of overpayments made to a federal fund to pay down debt and finance buyouts to 100,000 postal employees.
At the same, it would halt the closing of more than 100 mail processing centers, bar any shutdowns before the November elections and protect rural post offices for one year.
The issue now goes to the House, which has yet to consider a separate bill.
