So... as far as I can tell the apostrophes-to-question-marks behaviour has something to do with the way Mailman processes MIME-encoded messages. The sample message that Dylan sent to the Servers list (Innilgard_ Event Formerly Known as Spring Crown Tournament, 11-12 September.eml) has
Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: base64
I've verified that running the message content through base64 -i -d produces some HTML that displays the apostrophe correctly in a text editor using UTF-8. (It does, however, fail to decode without the -i, but this could be due to way I cut the text out of the message.) After passing through Mailman, the relevant headers become just
Content-Type: text/html;charset=utf-8
with the text no longer MIME-encoded and with a question mark replacing any non-ASCII characters. Messages sent directly from my e-mail clients have
Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
which passes through Mailman unchanged. Roundcube sidesteps the whole
issue by changing Æ to Æ and the apostrophe to ’ in the HTML
version of the message.
I haven't found where Mailman handles MIME-encoded messages and Selene
has just gone down again so that's it for today.
Ælfred
------ Original Message ------
From "Ælfred se leof via Selenetest"
... and testing from a different e-mail client: Ploughman’s Lunch
------ Original Message ------ From "Ælfred se leof via Selenetest"
To selenetest@lochac.sca.org Date 12/02/2023 3:09:54 PM Subject [Selenetest] Testing apostrophes Testing: Ploughman’s Lunch