Scalix runs its own instance of OpenLDAP for authentication purposes and by default this operates on port 389 which is the standard port for LDAP. The only problem with this is that you cannot run a 'proper' LDAP service (OpenLDAP, FedoraDS, eDirectory) on the standard LDAP ports without there being a conflict with the Scalix service. Fortunately there is a simple workaround that lets you run the Scalix service on a non-standard port.
Edit the /var/opt/scalix/sys/slapd.conf file and change the setting portNum to a non-standard (preferably high-level) port. In this example I will use port 6389 but it can be any port that is not currently being used by another service.
portNum 6389
Now edit the /etc/opt/scalix/caa/scalix.res/config/ubermanager.properties file and set the ubermanager.query.server.port to the same value:
ubermanager.query.server.port=6389
Save the changes and restart Scalix for the new LDAP port settings to take effect.