Re: [PATCH] pgarchives: parser: handle messages in which Message-ID is missing

> 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
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Célestin Matte