Viktor Dukhovni:
> On Sun, Jan 08, 2023 at 09:23:52PM +0100, Benny Pedersen wrote:
>
> > > I want again to state that header which says "Received: by
> > > <hostname> (Postfix, from userid <userid>)" is perfectly normal and
> > > expected Postfix behavior when mail is submitted locally. I have
> > > seen it countless number of times.
> >
> > maybe there is a valid reason postfix have 2 header formats ?
>
> Postfix has one "Received" header format, which is the one defined in
> RFC5021: https://www.rfc-editor.org/rfc/rfc5321#page-60
>
> This format has various optional elements, not all of which are
> applicable to every message. Postfix adds the required and reasonably
> applicable elements. The specification also permits unstructured
> comments (CFWS) between the various elements, this often include things
> like an IP address or string form of a timezone, etc.
>
> Any software that mandates non-required optional elements or particular
> content in comments is not portable. Any such expectations need to be
> configurable on a case-by-case basis, limited to processing messages
> generated in a known context that are then sure to include the expected
> elements.
Postfix blatantly copied this behavior from Sendmail, to not upset
common expectations in contemprary software.
Wietse
