Murray S. Kucherawy:
> Hi,
>
> I'm co-authoring a draft that would add supplementary information
> to Received header fields indicating when a message enters some
> kind of administrative hold. This would be useful to people looking
> through trace data to figure out why a message sat on a machine
> for some time, if the reason is something other than a hop that
> took a long time to complete for connectivity reasons.
>
> The draft specification is here:
> https://datatracker.ietf.org/doc/draft-kucherawy-received-state/
>
> Would postfix be willing to implement something like this? At a
> minimum, it might be useful to use this to indicate that a milter
> application requested that a message be quarantined until an
> operator released it.
The opportunities for doing this with Postfix are limited.
Postfix writes the Received: header at message arrival time. The
decision to add a Received: state field must be made before the
"250 OK" in response to end-of-data, after the message is frozen
(*). Once Postfix sends "250 OK" in response to end-of-data, there
is no way that a Received: header can be replaced without violating
the RFC requirement that mail not be lost due to frivolous causes.
Postfix stores the MTA's own Received: header right before the
message header and content. The stored header can be replaced via
the queue file editing routines that support the Milter protocol.
I recall that for Sendmail compatibility reasons, those routines
do not allow Milters to manipulate the MTA's own Received: header,
but I guess some checks could be moved around so that the edit
routine can go to places where Milters cannot.
Wietse
(*) Recipients are deleted by in-place overwriting a status byte,
which is assumed to be an atomic operation.
