s/mail is software that encrypts and digitally signs emails. It is realized as a plugin for Microsoft Outlook and IBM Notes. The user-interface is seamlessly integrated into the respective email client.

s/mail is PKI-based and compliant with all relevant standards. It supports X.509v3 certificates as well as the S/MIME 3.0 format for encrypted and signed emails. Revocation checks are performed via X.509v2 revocation lists or OCSP.

Contrary to an email crypto gateway, s/mail enables end-to-end security. Compared to the built-in mail encryption functions of Outlook and Notes, s/mail provides a higher security level, as it features encap-sulated crypto functions and advanced smart card support.

In addition to security, convenience for both users and administrators have been important design-goals in the development process of s/mail. User interaction is kept to a minimum, encryption and signing are performed automatically. Flexible group policies allow for easy administration and pre-configuration.