19. A method for locating a certificate for an electronic messaging system, wherein acts of the method are performed by a processor of a computing device, the acts comprising: searching for a certificate of a sender of an electronic message based on a canonical name associated with a sender address of the sender, wherein the sender address comprises at least a first user name and at least a first domain name and wherein the canonical name is the sender address with both the first domain name truncated to identify a second domain name and the first user name truncated to identify a second user name.
19. A method for locating a certificate for an electronic messaging system, wherein acts of the method are performed by a processor of a computing device, the acts comprising: searching for a certificate of a sender of an electronic message based on a canonical name associated with a sender address of the sender, wherein the sender address comprises at least a first user name and at least a first domain name and wherein the canonical name is the sender address with both the first domain name truncated to identify a second domain name and the first user name truncated to identify a second user name. 22. The method according to claim 19 , wherein the searching for the certificate of the sender of the electronic message based on the canonical name associated with the sender address of the sender comprises: searching for the certificate of the sender based on the sender address with the first domain name truncated to identify the second domain name, and searching for the certificate of the sender based on the sender address with the first user name truncated to identify the second user name, concurrently.