Sign in Microsoft Word
USPS EPM Extension for Microsoft Office lets you digitally sign Word documents and seal them with the trusted USPS Electronic Postmark (USPS EPM).

Verify with USPS Trust
Just click the USPS EPM icon in the Microsoft Word toolbar, apply a USPS EPM to your document (contract, letter, agreement), and sign. This gives your document tamper protection against fraud and the ability to verify document authenticity with a click of the USPS EPM signature block. Evidence of document authenticity is stored in the USPS EPM repository for seven years to ensure trusted non-repudiation of content.

You will need a digital certificate to use this software.
The Certificate