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How does envelope change?

I'd like to understand the differences in the envelope fields at points
where external filtering can happen:

* content_filter when receive_override_options=no_address_mappings (sent
to filter via SMTP)

* content_filter when address mappings have occurred (sent to filter via
SMTP)

* in the delivery agent (given to delivery agent via LMTP)

How would a content filter see the envelope fields in these cases? What
fields change? Can adding a X-Original-To header help the delivery agent
see the message as originally received? (Is this possible in Postfix?)

Off-topic part is whether anyone knows the effects any such changes
would have on spam filtering?

I also assume multi-recipient messages would be filtered multiple times
if done in delivery vs. in content_filter.

Comments

Re: How does envelope change?

By Noel Jones at 11/22/2016 - 16:46

On 11/22/2016 3:06 PM, MRob wrote:
please see:
<a href="http://www.postfix.org/ADDRESS_REWRITING_README.html" title="http://www.postfix.org/ADDRESS_REWRITING_README.html">http://www.postfix.org/ADDRESS_REWRITING_README.html</a>
<a href="http://www.postfix.org/OVERVIEW.html" title="http://www.postfix.org/OVERVIEW.html">http://www.postfix.org/OVERVIEW.html</a>

Minimal to none, unless you're trying to apply different filter
rules depending on the recipient. In that case, the details are
documented;
<a href="http://www.postfix.org/documentation.html" title="http://www.postfix.org/documentation.html">http://www.postfix.org/documentation.html</a>

-- Noel Jones