I'd like to reheat the proposition that we enable discussion feature on GitHub for the repos. Not only this makes things a bit more streamlined (transfer nonbug reports to discussions to handle noise there) but also makes it easier to control the discussions. Moreover since it is GitHub there are API-based ways to import mailing lists for NumPy and SciPy with a bit less effort.
This was discussed in the community meeting today. No one was really enthusiastic, concerns that were brought up included the lack of an email interface, and an unclear boundary between issues and discussions.
If we move, importing the mailing list archives will clearly be important though, any replacement should be able to do this.
Cheers,
Ralf