Google Outbound Services Configuration Guide - Manual (Page 43)

Microsoft Exchange 2007/2010 (Private DNS Method) 45
6. In the nslookup prompt, type gmail.com again. You should see a different IP
address now. If you see an error message, your network settings are blocking
your DNS connection.
7. In the nslookup prompt, type server [old default server] to restore your
default server. Substitute your previous default server name for [old default
server] .
8. Press Control-C to exit nslookup.
I am still seeing mail queueing
Your mail is still being routed through a smarthost. Try the following steps:
1. If you set up a smarthost to route mail to Outbound Servers, disable the
smarthost.
2. Restart your mail server.