Something came up last time Sourceforge was discussed here, namely "why are projects still using it?"...

I'm the project lead for LXQt (http://lxqt.org). We inherited some infrastructure legacy from LXDE, which was hosted on sourceforge. Today, we have moved most of the legacy to Github but we're still using Sourceforge's mailing list system.

We're moving to a self-hosted mailman3 instance but it's been excruciatingly painful. Email is not fun to deal with.

So I'm pitching this to bored devs and entrepreneurs: Help us, and many other projects, by creating a "Github for mailing lists" with a web client featuring a clean high quality UI, easily browsable/linkable archives, etc. Make it open source, make it self-hostable, stuff in enterprise support. Make it quick and easy to create new lists.

This model can work. It's not unheard of either (cf. Discourse), but it just hasn't been executed properly yet, or is forum-only and does not support email properly. Right now, the UX of mailing list software is like IRC's. Very raw. If it were made more seamless, more approachable, overall easier, it would have a similar effect as Slack has had on unthreaded-async-topical-conversation.

PS: You should change your adblocker to uBlock Origin. It blocks Sourceforge as a malware risk.