Hi Mathieu, Questions around this, are probably better directed at syst...@php.net, but it's here now, so I'll answer.
On Thu, 31 Jul 2025, Mathieu Rochette wrote: > At work we built a feature in a mail client that deals with > newsletters subscriptions. > > Subscriptions are identified by messages having a List-ID or > List-Unsubscribe header. Then, to differentiate mails being > newsletters or list discussions, one heuristic is to look at the > `Precedence` header, it can be `bulk` for mass mailing (so > newsletters) or `list` (discussions). And when working on that I > noticed that PHP lists were wrongly sent the mails with `Precedence: > bulk`. Is this something that could be fixed? I can certainly change the "Precedence: bulk" header to "Precedence: list". I would have to do that for all our 124 lists, but I am moderately reluctant in doing this, as Google is being annoying requiring specific things for email delivery, and I don't want to upset them again. > It's not a big deal since I've since added another heuristic that > works woth the PHP mailing lists (classify subscription as discussion > is it has a `List-Post` header) but wanted to let you know, it may be > useful for other clients if / when they implement features using those > headers. > > Also, the List-ID is not properly formatted, it's supposed to be > wrapped in angle brackets but it's not, so instead of `List-Id: > internals.lists.php.net` it should be `List-Id: > <internals.lists.php.net`> or even ``List-Id: PHP Internals > list <internals.lists.php.net> to give it a human friendly name. One > downside of fixing it though is that it may break automatic filtering > rules of people matching exactly `List-Id: internals.lists.php.net`.`` We can easily change the List-Id header too, as long as I don't need to add a manual description to all 124 of them. So for now, I would suggest to change them to "List-Id: <internals.lists.php.net>". Would that work? cheers, Derick -- https://derickrethans.nl | https://xdebug.org | https://dram.io Author of Xdebug. Like it? Consider supporting me: https://xdebug.org/support mastodon: @derickr@phpc.social @xdebug@phpc.social
