Mailman used to be standard some decades ago, but fresh users don't know how to work with it. Other software-as-a-service providers try to assimilate users on their own account, e.g. stackoverflow.
Various high-end projects now have a self-hosted instance of https://discourse.org to make the best out of old and new traditions.
Is it feasible to use it as a replacement for Mailman mailing lists, issue trackers, and fancy games like zulip at the same time?