With the explosion of the public Internet and e-commerce, private computers, and computer networks, if not adequately secured, are increasingly vulnerable to damaging attacks. Hackers, viruses, vindictive employees and even human error all represent clear and present dangers to networks. Various antidotes that are in fact inextricable with security issues are - Cryptography, Authentication, Integrity and Non Repudiation, Key Distribution and certification, Access control by implementing Firewalls etc.The main idea of this paper is to overcome the PGP's(Pretty Good Privacy) main limitation of incomplete non-repudiation Service, which increases the degree of security and efficiency of an email message communication through NRR(Non-Repudiation of Receipt) and including PGPs original feature of NRO(Non-Repudiation of Origin), and there it assures new security service of Mutual Non-Repudiation (MNR) .