sean
Thanks for this suggestion. I'll probably give that a try today and see how it works if you suggest it's going to be one of the more compatible options with OpalStack.
To answer your earlier question, in my case a simple listserv-like functionality will do the trick. I also discovered https://www.sympa.org/ and thought maybe that would work, but I admit that mailing list functionality is something I don't know a lot about.
My use case: neighborhood/community that needs an easy way to send notices/announcements to each other, where many of the users are not very tech savvy and need a very simple way to interact (ie. email). infrequent and usually brief messages or conversations like "trash service will be delayed this week" or "does anyone know who is in my parking space" or "would anyone like to do a neighborhood bonfire on Friday?"
Thanks!