Email Formats

{
  "mx": [
    "10 mx3c28.concentric.com.",
    "20 mx4c28.concentric.com.",
    "0 mx1c28.concentric.com.",
    "5 mx2c28.concentric.com."
  ],
  "spf": [
    "v=spf1 mx a ptr ?all"
  ]
}