https://meta.wikimedia.org/wiki/Interwiki_map says:
Mail https://lists.wikimedia.org/postorius/lists/$1.lists.wikimedia.org/
For example, [[mail:analytics]] goes to https://lists.wikimedia.org/postorius/lists/analytics.lists.wikimedia.org/
That works fine but it means [[mail:]] alone or mail: in a searchbox goes to https://lists.wikimedia.org/postorius/lists/.lists.wikimedia.org/
This gives a 404 not found. I suggest redirecting that page to https://lists.wikimedia.org/postorius/lists/
The 404 page does have a "Lists" link at top which goes where I want but nearly all interwiki links with nothing after the colon work better by taking you to the main page, usually via a redirect. For example, [[wiktionary:]] goes to https://en.wiktionary.org/wiki/ which redirects to https://en.wiktionary.org/wiki/Wiktionary:Main_Page
The poor cases are mostly/only when $1 is not at the end.

https://lists.wikimedia.org already redirects to https://lists.wikimedia.org/postorius/lists/. I just request the same result for [[mail:]]. A double redirect via https://lists.wikimedia.org would also be OK.