[mail-vet-discuss] Removing A-R headers fields

Murray S. Kucherawy msk at cloudmark.com
Mon Feb 8 10:37:15 PST 2010

> -----Original Message-----
> From: mail-vet-discuss-bounces at mipassoc.org [mailto:mail-vet-discuss-
> bounces at mipassoc.org] On Behalf Of Alessandro Vesely
> Sent: Monday, February 08, 2010 9:53 AM
> To: mail-vet-discuss at mipassoc.org
> Subject: [mail-vet-discuss] Removing A-R headers fields
> (is this list still active?)
> Section 5 of rfc5451 says:
>    An MTA SHOULD remove any instance of this header field bearing a
>    version (express or implied) that it does not support.  However, an
>    MTA MUST remove such a header if the [SMTP] connection relaying the
>    message is not from a trusted internal MTA.
> I'm puzzled about the "trusted internal" qualification. Assuming that
> "internal" is relative to an ADMD, "trusted" seemingly means the
> opposite of "compromised". Or was that meant to be "trusted _or_
> internal"? Perhaps, a trusted forwarder's A-R fields could be let
> alone...

It's meant to distinguish between an internal MTA maintained by, for example, an ADMD's IT department versus one on someone's desktop.  "Compromised" is one possibility for exclusion; "unauthorized" is another.

> BTW, any pointer to current deployments of this field?

Speaking only from personal experience, Google, Yahoo, dkim-milter, opendkim, dk-milter (deprecated), sid-milter all use it.

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