Patent ID: 8667271

Claim:
A method of resolving message addresses of a message to be encrypted, the method comprising: a) looking up, from a user cache, a user address associated with a message address, and determining that the lookup returns that the message address is unresolved, thereby indicating that the message address had been previously looked up as a user name in a source directory but was not found, treating the message address as a group address, by: a. looking up, from the source directory, a group name associated with the message address and one or more user names for members of the group associated with the group name; b. looking up an user address for each of the one or more user names from the user cache; c. if the user address associated with the user name is not found in the user cache, then looking up the user address associated with the user name from the source directory, and if the user address is returned then adding the user address associated with the user name to the user cache for future lookups; d. if the user address associated with the user name is not found in the source directory then adding the user name as an unresolved message address in the user cache and treat the user name as a group address, returning to a); b) looking up, from the user cache or the source directory, encryption keys for encryption associated with each of the one or more user names; c) addressing the message to the looked up user addresses and encrypting the message using the looked up encryption keys; and d) transmitting the message to each looked up user address.