and, of course... $ host smtp-relay.gmail.com smtp-relay.gmail.com has address 74.125.142.28 smtp-relay.gmail.com has IPv6 address 2607:f8b0:400e:c08::1c $ whois 74.125.142.28 ... NetRange: 74.125.0.0 - 74.125.255.255 CIDR: 74.125.0.0/16 NetName: GOOGLE NetHandle: NET-74-125-0-0-1 Parent: NET74 (NET-74-0-0-0-0) NetType: Direct Allocation OriginAS: Organization: Google LLC (GOGL) RegDate: 2007-03-13 Updated: 2012-02-24 Ref: https://rdap.arin.net/registry/ip/74.125.0.0 ....