173.194.0.0/16
209.85.128.0/17
216.239.32.0/19
216.58.192.0/19
64.233.160.0/19
66.102.0.0/20
72.14.192.0/18
74.125.0.0/16

# https://support.google.com/a/answer/60764?hl=en