MailAuth.AuthenticationResults (MailAuth v0.1.0)

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Writes and reads Authentication-Results: headers (RFC 8601).

Trust

Anyone can write an Authentication-Results: header. RFC 8601 says to read one only when it comes from a server you were told to trust, and to remove the ones claiming to be from your own servers when mail arrives. parse/2 marks each header trusted? only when its authserv_id is in the :trusted list, and never trusts a header without one (as Outlook writes them).

Checking DKIM and DMARC yourself, with MailAuth.authenticate/2, needs no trust in any header.

Summary

Types

t()

Functions

format(result, authserv_id)

Writes the Authentication-Results: header for a MailAuth.Result, under authserv_id, the name of your server. Returns the whole header field, folded, without a final line break.

parse(input, opts \\ [])

Reads every Authentication-Results: header in a message, or one header (with or without its name).

Types

t()

@type t() :: %MailAuth.AuthenticationResults{
  authserv_id: String.t() | nil,
  results: [MailAuth.AuthenticationResults.Method.t()],
  trusted?: boolean(),
  version: String.t() | nil,
  warnings: [atom()]
}

Functions

format(result, authserv_id)

@spec format(MailAuth.Result.t(), String.t()) :: String.t()

Writes the Authentication-Results: header for a MailAuth.Result, under authserv_id, the name of your server. Returns the whole header field, folded, without a final line break.

iex> result = %MailAuth.Result{dkim: [], spf: %MailAuth.SPF.Result{result: :none, reason: :no_client_ip}}
iex> MailAuth.AuthenticationResults.format(result, "mx.example.com")
"Authentication-Results: mx.example.com; none"

parse(input, opts \\ [])

@spec parse(binary(), keyword()) :: [t()]

Reads every Authentication-Results: header in a message, or one header (with or without its name).

Options:

  • :trusted: the authserv_ids to trust, such as ["mx.google.com"]. Compared without case

Unknown methods are kept. A header that can't be read in part gives what could be read and the warning :malformed.