Yes, postal service workers are civil servants and can take the following deduction if it applies. You will be asked about this or any credits available to you as you go through the Ohio program.
"Federal civil service retirees who received federal service credit for military service are allowed to deduct only that portion of their pension attributable to military service. A formula for this deduction can be found in the Ohio income tax instructions under the Schedule A deductions. " From the Ohio tax web site.
