Message-ID: <72c93f94-1968-3939-2686-8e36e65b38fe@cmatte.me>
Date: Fri, 5 Nov 2021 12:31:23 +0100
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To: Magnus Hagander <magnus@hagander.net>,
 Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: pgsql-www@lists.postgresql.org
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 <202111041947.x5su2sdjdx74@alvherre.pgsql>
 <CABUevEyhYyx4DJ_7kENZry2wwZYz9R4J_oh8f0cKkUY+3Q8Kfw@mail.gmail.com>
From: =?UTF-8?Q?C=c3=a9lestin_Matte?= <celestin.matte@cmatte.me>
Subject: Re: [PATCH] pgarchives: parser: handle messages in which Message-ID
 is missing
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> Have you actually come across any case where a *proper* non-spam message is sent without a message-id and passes through actual mailservers on the way? 
> 
> Looking through the approximately 1.4 million mails in the postgres list archives, not a single one has a message-id generated by the archives server MTA (which is configured to generate it). Not a single one by our inbound relay servers. And exactly one by the pglister server -- which turns out to be a bounce that ended up in the archives because of a misconfiguration back in 2018 that's not visible in the public archives.

After some tests, I do have a very few number of non-spam examples (3 emails from 2 different people in a postfix+mailman mbox of 5k emails), but they date from 2003-2007.

Exim already handles empty Message-IDs by default by generating them [1], although it will let a message with Resent-Message-ID pass through as-if. I tested such a case, and pglister seems to actually drop the message (or fail silently).


[1]: https://www.exim.org/exim-html-current/doc/html/spec_html/ch-message_processing.html#SECID226
-- 
Célestin Matte