Skip to content

kumo.spf.check_msg

kumo.spf.check_msg(MESSAGE, OPT_RESOLVER_NAME)
Since: Version 2025.12.02-67ee9e96

The functionality described in this section requires version 2025.12.02-67ee9e96 of KumoMTA, or a more recent version.

This function will check SPF records from DNS for the provided message. It will extract the appropriate domain and sender information from the metadata and message.

It will return an object containing the SPF disposition string and a result of type authenticationresult for use with msg:add_authentication_results().

The OPT_RESOLVER_NAME parameter is an optional string parameter that specifies the name of a alternate resolver defined via kumo.dns.define_resolver. You can omit this parameter and the default resolver will be used.

Example: checking the SPF policy

kumo.on('smtp_server_message_received', function(msg, conn_meta)
  -- Check the SPF policy for the domain and return the results.
  local result = kumo.spf.check_msg(msg)
  print('spf', kumo.json_encode_pretty(result))
  if result.disposition ~= 'pass' then
    kumo.reject(420, 'go away')
  end
end)

might print something like this to the diagnostic log:

spf    [
  "disposition": "pass",
  {
    "result": "pass",
    "method": "spf",
    "reason": "matched 'all' directive",
    "method_version": null,
    "props": {
        "smtp.mailfrom": "sender@example.com"
    }
  }
]

See Also: