If you work for the post office, you're a civil servant. The Civil Rights movement focused on the notion that all American citizens were entitled to the same basic civil liberties.
There is also time limit to consider for sending the amended returns, and it is generally three years from the time you filed the returns or two years after the tax payment (whichever is later). If you plan to amend more than one tax return, you have to file separate 1040X for every one you want to change.
Generally an IRS tax lien will automatically release 10 years (from the date of assessment) after it was filed. However, the IRS may re-file liens under certain circumstances. So the key date is ten years from the date of the final notice and assessment of tax due for the tax year in question. If subsequently, you have not been notified that the tax lien was re-filed you should request a Certificate of Release of Federal Tax Lien. IRS Publication 1450 can give you specific instructions on how to do this. See it at http://www.irs.gov/pub/irs-pdf/p1450.pdf.