Google Outbound Services Configuration Guide - Manual (Page 92)

Microsoft Exchange 2007 with an Edge Server (Smarthost method) 97
Troubleshooting
Installing Exchange 2007 onto an existing Exchange 2003 environment
If you've installed Exchange 2007 into an existing environment with 2003, you
may already have a Send Connector (SMTP Connector). If so, modify and verify
your settings there. If the connector is on your 2003 server, you can only view the
settings from the Exchange 2007 Management Console. Make all changes
through from the Exchange 2003 System Manager (look for “SMTP Connectors”).
For example, if you only have a connector on the 2003 machine, then all outbound
mail will go through the 2003 server. If you have one on the 2003 and one on the
2007 server, then mail will go through the closest connector. If you delete the one
on 2003 and have one on the 2007 server, then all outgoing mail will pass through
the 2007 server.