I have included _spf.google.com in my company's domain SPF record as describe in Google Apps help - http://www.google.com/support/a/bin/answer.py?answer=60764
_spf.google.com IN TXT v=spf1 ip4:184.108.40.206/19 ip4:220.127.116.11/19 ip4:18.104.22.168/20 ip4:22.214.171.124/18 ip4:126.96.36.199/17 ip4:188.8.131.52/20 ip4:184.108.40.206/16 ip4:220.127.116.11/20 ip4:18.104.22.168/20 ip4:22.214.171.124/16 ?all
But from the email header I can see that it is sending out from mail-px0-f172.google.com (126.96.36.199) which is not in the above ip address range. The most closely matched is ip4:188.8.131.52/17. Am I or Google missing something here? Any help is very much appreciated!