Sunset mailing group

[icweaver]

Just opening this here as a tracking issue brought up from our old matrix/element instance

To be more in line with our OpenAstronomy presence (OpenAstronomy/openastronomy.github.io#388), should we start phasing out our mailing group in favor of our Discourse? From the website side of things, I think this would just be deleting this line (#122):

JuliaAstro.github.io/docs/src/index.md

Line 21 in bbfae19

- [julia-astro](https://groups.google.com/forum/#!forum/julia-astro) mailing list on Google Groups

From the mailing group side of things, perhaps we could follow similar guidance from the old Julia mailing group migration, e.g., direct mailing group users to set up up email forwarding on Discourse posts?

[icweaver]

Copying a follow-up response here from Mosè:

I'm in favour of this, especially because this mailing list has been pretty much inactive over the last 5 years (1 conversation per year since 2020). I don't know how to technically sunset it, but for the time being I

• restricted new members to invited users
• added a message to the description of the group indicating that this deprecated in favour of > Discourse
• added the same message as welcome message for new members indicating that the mailing list is > deprecated (this is made redundant by the first point above, but never enough)

Another possible action is to restrict posting new messages to managers/owners.