A bulk import from a file that had a stray `?` in it caused someone to be subscribed akin to `first.last?@example.com` While postorious correctly makes that `%3F` in the URLs, it generates a `404` from the `DELETE` request in the underlying API: `DELETE http://10.10.10.10:8001/3.0/lists/my-list.lists.example.com/member/first.last?@example.com [404]` And indeed, `https://lists.example.com/mailman3/postorius/lists/my-list.lists.example.com/members/options/first.last%3F@example.com` throws up a 404 as well. Sadly this `404` is surfaced to the admin trying to manage things as a bare `500`, which made diagnosis difficult.