- Log on to the Client Access server (CAS) to which the users are connected, and then locate the following folder that stores the log file: C:\Program Files\Microsoft\Exchange Server\V14\Logging\RPC Client Access
- Open the RCA-YYYYMMDD-X.log file, and then search events that are related to the users in question. For example, you find the following information:
- Copy the LegacyexchangeDn information of the user. For example, copy the following:
- In Active Directory Users and Computer (ADUC), right-click the domain object, and then click Find.
- Click the list next to Find, and then select Custom search.
- Click Advanced, type the following Lightweight Directory Access Protocol (LDAP) statement under Enter LDAP query, and then click Find Now:(proxyaddresses=X500:/O=Contoso/OU=First Administrative Group/cn=Recipients/cn=USERTest)C
- Determine whether any duplicate users are returned.
- Check the X500 address of any returned users, and then remove the duplicate proxy address for those users.
- (proxyaddresses=X400:C=US;A= ;P=Contoso;O=First Administrative Group;S=User;G=Test)
- (proxyaddresses=X500:/o=Contoso/OU=First Administrative Group/CN=Recipients/CN=TestUser)