Since they seem to have zillions of outbound mx machines I did this in response to some email latency issues.
dig google.com txt google.com. 31 IN TXT "v=spf1 include:_netblocks.google.com ~all" then i dig _netblocks.google.com txt _netblocks.google.com. 47 IN TXT "v=spf1 ip4:216.239.32.0/19 ip4:64.233.160.0/19 ip4:66.249.80.0/20 ip4:72.14.192.0/18 ip4:209.85.128.0/17 ip4:66.102.0.0/20 ip4:74.125.0.0/16 ip4:64.18.0.0/20 ip4:207.126.144.0/20 ?all" Are most of you whitelisting these blocks ? has anyone noticed if these are pretty static or do these TXT records change frequently or otherwise? - rh
