johannes.wolf--- via Mailman-users writes:
Unfortunately, we can't find out how to customise the subject of the email. Can anyone help us here?
You can add a prefix in Settings > List Identity > Subject Prefix. If you want the conventional square brackets "[]" you must put them in yourself. If you want a serial number, you can add a Python "%d" spec (you can specify the width and zero-padding as usual). You cannot customize the serial number itself. I believe it resets every time the digest volume number is incremented.
If you want more than that, that's the responsibility of the MUA.
-- GNU Mailman consultant (installation, migration, customization) Sirius Open Source https://www.siriusopensource.com/ Software systems consulting in Europe, North America, and Japan