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Re: Is Return-Path as available as we think?

2004-02-02 14:26:22
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wayne writes:
In 
<0A78B84D9FDBFE41A53D4389657AACA0BB4E89(_at_)radon(_dot_)vidius(_dot_)co(_dot_)il>
"Arik Baratz" <arikb(_at_)vidius(_dot_)co(_dot_)il> writes:


Well, I was geared towards doing just that, but I didn't get a single report
of an MTA's non-compliance yet.

IIRC, Justin Mason said that fetchmail can mess things up.

Yep.  here's the timeline of how this can happen:

- - message hits a mailing list app which records the original
  envelope-from in an "X-Sender" header, e.g. ezmlm.

- - ezmlm resends message with new envelope-from.

- - delivered to recipient, with headers like:

      Return-Path: <ezmlm-env-from(_at_)example(_dot_)com>
      Received: ... [IP of list server]
      X-Sender: <original-env-from(_at_)example(_dot_)com>
      Received: ... [IP of original sender]
      Received: ...
      From: ...
      Subject: ... etc.

- - fetchmail then downloads the message, and looks for an env-from to use
  when it resends it.  It picks the X-Sender header over the
  Return-Path, unfortunately.  There's the error...

- - this results in:

      Return-Path: <original-env-from(_at_)example(_dot_)com>
      Received: ... [IP of list server]
      X-Sender: <original-env-from(_at_)example(_dot_)com>
      Received: ... [IP of original sender]
      Received: ...
      From: ...
      Subject: ... etc.

- - == SPF fail, because 'IP of list server' isn't permitted for
  'original-env-from(_at_)example(_dot_)com'.

The way to avoid that: skip messages where 'X-Sender' appears, and
Received contains 'fetchmail'.

- --j.
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