Google Outbound Services Configuration Guide - Manual (Page 41)

Microsoft Exchange 2007/2010 (Private DNS Method) 43
12. Choose “Use domain name system (DNS) MX records to route mail
automatically.” Do not route mail through a smart host.
13. Check “Use the External DNS Lookup settings on the transport server.”
14. Click OK to exit the dialog.
15. In the Exchange Management Console, restart your server.
Test Outbound Mail
Once you have set up Private Outbound DNS, test that your configuration is
correct and mail is flowing normally.
Test the configuration.
1. Go to the Queues tab in Internet Mail Service Properties. Items with a retry
state could indicate outbound mail delays.