Microsoft has forced all developers to use a code signing certificate that uses the SHA-256 algorithm in order for signatures to be recognized on Windows 7+, as of Jan 1 2016. See http://aka.ms/sha1 for the full details but the consequence of Microsoft's decision means that our SHA-1 certificate that we received needed to be replaced.
Today SHA-1 certificate has been replaced by new SHA-256. kSign version has been updated as well to support that new certificate. As a test MaxBulk Mailer distribution file has been built successfully!