Evaluating an SPF Record

• Works like a firewall policy:

• • Evaluate mechanisms in order from first to last
  • If the mechanism results in a match, it’s prefix value is used (default is pass (+))
  • If no mechanism or modifier matches, the default result is neutral
  • Most SPF records end in a catch-all rule called “all”
  • • Prefixed with a “+” (+all), this rule is an ALLOW all
    • Prefixed with a “-” (-all), this rule is a DENY all