Google Apps Directory Sync for Postini Services Administration Guide - Manual (Page 30)

Configuration 33
Test Connection
Once you have configured Server settings, click Test Connection. Configuration
Manager will connect to the message security service and attempt to log in.
If the test fails, verify your admin email and password, and confirm that you are
able to connect to the Internet from the machine.
Message Security Service Orgs
On this page, specify which orgs in the message security service to synchronize.
The directory sync utility will use these orgs to generate user lists as a basis for
comparison with your LDAP user list.