Most online communities these days are web-based, and support editing and deleting community content (among other things). Before web fora there were (and still are) mailing lists, which can also function as communities. Mailing lists, unlike web-based communities, are write-once -- no editing or deleting community-wide. (Of course, individual recipients can do whatever they want with the messages they receive.)
Are questions about the community/people aspects of mailing lists on-topic here?
Moderators.SE is (and in the proposal already was) intended to be about communities. There's a reason the matter of community management was brought up repeatedly. Of course that means mailing lists are on-topic as well - the behavioural patterns and required oversight, are similar.
The site does not even need to restrict itself to written or online communication, for that matter. Mostly anything that fits the topic of maintaining, managing and navigating a community should be perfectly on-topic.
