Returns the full name associated with a user ID in an Address Book.
AFTKN_AB_GET_FULLNAME or 818
ANSISTRING AddressBookGetFullName (ANSISTRING FullAddressText; [ANSISTRING UserID])
EmailAddress in the form "Domain.PostOffice.UserID." Will also except UserID as well as EmailAddress.
(Optional) User ID of the mailbox that contains the Address Book information. Use this parameter to search a proxy mailbox.
The descriptive name or displayName displayed to the user.