Sorry to see there has been no mention of Zulip so far. I fooled around with Slack a little, and then Zulip. And in my opinion zulip hit that sweet spot between email and chat. I really like the way conversations can be segregated into actual conversations. The trick to using it, I've found, is to set team expectations that posts might not be replied to until later in the day. There is something subtle about slack that sets your expectation for immediate gratification, and that drives the exhausting 'always on' culture.

I imagine you are all relishing that sweet irony/hypocrisy of a tool that facilitates distributed work, not permitting its team to work in a distributed fashion. Culture fail!

Fifteen years ago or more, I was able to work pretty effectively with a team using email and IRC. I know IRC is out of fashion now, but my point is that a lot of the challenge is team culture and expectations, and software doesn't really fix that problem.