postmarking

"You want to be able to trust what's inside," Mr. Weinstein said in a telephone interview, adding that since Microsoft and Authentidate own the software, only those companies know precisely how electronic postmarking works.

A Digital Postmark (DPM) is a technology that applies a trusted time stamps issued by a postal operator to an electronic document, validates electronic signatures, and stores and archives all non-repudiation data needed to support a potential court challenge - it guarantees the certainty of date and time of the postmarking.