Google Apps mail servers MX Records

To deliver mail to Gmail inboxes, configure your domain to route incoming
messages to the Google email servers. To do that, add MX records that point to
the Google servers shown in the table below.

See Creating MX records for details
about adding MX records to your domain.

Priority Mail server
1 ASPMX.L.GOOGLE.COM
5 ALT1.ASPMX.L.GOOGLE.COM
5 ALT2.ASPMX.L.GOOGLE.COM
10 ASPMX2.GOOGLEMAIL.COM
10 ASPMX3.GOOGLEMAIL.COM

Note: The values in the Priority column show the
relative priorities of the Google servers. The values do not need to be
exactly those shown in the table; different domain providers have different
systems for setting MX record priority. Regardless of the system,
ASPMX.L.GOOGLE.COM must be the top priority record.

http://www.google.com/support/a/bin/answer.py?answer=174125