They provide plain good ol' GNU Mailman lists. You can bring your own domain or subdomain. They also have a good handle on privacy issues (GDPR requests and so on).
Related to this topic (spouse with Alzheimer), there is a touching story by Alice Munro: "The Bear Came Over the Mountain", the closing story of the book "Hateship, Friendship, Courtship, Loveship, Marriage".
«basedir: support separate (vendor/local) trees and masking for config files» https://gitlab.freedesktop.org/xdg/xdg-specs/-/merge_request...
«basedir: support drop-ins for configuration paths» https://gitlab.freedesktop.org/xdg/xdg-specs/-/merge_request...