] Almost every email client in existence today has the
] ability to verify a digital signature in either S/MIME
] and/or PGP. S/MIME is arguably the more ubiquitous of the
] two, as most enterprise-level email clients come with
] S/MIME built in, including a repository of root
] certificates to form the basis of trust in verifying a
] digital signature on an incoming message.

Hi, this is what I do.

Digital Signatures Key to Solving Email Woes