procmail
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Re: Delivered-To: [adding it]

1999-06-16 16:19:43
Liviu Daia <Liviu(_dot_)Daia(_at_)imar(_dot_)ro> writes:

On 15 June 1999, Harry Putnam <reader(_at_)newsguy(_dot_)com> wrote:

Can be forwarded from those machines with a header added to make them
easily filterable when they arrive at:
reader(_at_)newsguy(_dot_)com

Most of the time this is accomplished by filtering on the "To: "
header, but in those cases where the "To " address, for one reason
or another is not present, then it becomes a project to filter them.
Much easier to just add a header at the forwarding end.
[...]

    Basically, you want to filter messages by the envelope recipients.
This can't be done, period.  Procmail is a delivery agent, not a MTA, so
it doesn't have access to envelope recipients.  By the time the message
gets to procmail the envelope recipients are already lost.

Not clear what you are saying above.  Do you mean a header cannot be
added by formail, through a procmail recipe?  Its a bit confusing to
hear: you should "filter messages by envelope recipients".
"Procmail... . doesn't have access to envelope recipients"
It would seem the conclusion would be [ procmail cannot filter messages ]
I know thats not what is meant here.   

    Even without it, messing with "Delivered-To:" and / or relying on
its contents is a bad idea.  Some MTAs out there (QMail and Postfix come
to mind) use that header for detecting mail loops, and they might add
such headers for messages in transit.

Is there a neutral header option that could be added in this situation
that doesn't cause other problems, but would make the messages easily
identifiable as to where they  came from?

I realize "Recieved" headers do this, but not in an easily parsed manner.

I want to do this:

[Incoming Internet mail] ==> [Machine 1 forwards to] => [machine  2]

At machine1 add, something innocuous to make mail easily identifiable
at machine 2.  So that recipient[s] at machine 2 can tell the mail was
first delivered to machine 1.