Regarding the url change:
> <https://lists.wikimedia.org/mailman/listinfo/wikitech-l> will change to
> <https://lists.wikimedia.org/postorius/lists/wikitech-l.lists.wikimedia.org/>

Is there a technical reason which requires including the list domain ine name?
I would seem preferable by far to use instead:
https://lists.wikimedia.org/postorius/lists/wikitech-l

and since all (?) our lists are using @list.wikimedia.org, it's not like we need the domain there to disambiguate it.

Cheers