If your directory does not use the uid attribute for user authentication, you need to configure the Instant Messaging server with the attribute used by your directory. By default, Instant Messaging uses uid. You also need to change each filter parameter that contains uid in its value.
Use the iim_ldap.loginfilter parameter to specify which attribute to use for user authentication.
Open iim.conf.
See iim.conf File Syntax for instructions on locating and modifying iim.conf.
Search for and replace uid with the attribute you want to use for user authentication in the following parameters:
iim_ldap.loginfilter
iim_ldap.usergroupbyidsearchfilter
Save and close the file.