13. A method for locating a certificate in an electronic messaging system, wherein acts of the method are performed by a processor of a computing device, comprising: obtaining a sender address for an electronic message received by the electronic messaging system, said sender address comprising a first user name and a first domain name; searching for a certificate of the sender based on a match with the sender address; automatically searching for the certificate of the sender based on a canonical name associated with the sender address if no certificate of the sender is found based on a match with the sender address, 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; and providing an indication of whether the certificate of the sender has been found.
13. A method for locating a certificate in an electronic messaging system, wherein acts of the method are performed by a processor of a computing device, comprising: obtaining a sender address for an electronic message received by the electronic messaging system, said sender address comprising a first user name and a first domain name; searching for a certificate of the sender based on a match with the sender address; automatically searching for the certificate of the sender based on a canonical name associated with the sender address if no certificate of the sender is found based on a match with the sender address, 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; and providing an indication of whether the certificate of the sender has been found. 18. The method according to claim 13 , wherein said canonical name comprises at least one of multiple canonical domain names and multiple canonical user names.