Electronic mail on the Internet has been an important form of communication for some years now. Various methods of securing electronic mail have been suggested (see our overview in section ). One of the solutions that has seen commercial success is S/MIME. A major problem in using S/MIME to secure mail is locating certificates. Clients often support several methods to locate certificates, ., from LDAP servers or from white-pages on the Internet. Most of these services have the drawback of requiring configuration by the user; configuration of the LDAP server hostname, the address to the whitepage service, of the LDAP base objects, etc