> Different stroke for different folks, but I'm still very much in the paradigm where email is more like a letter in the mail, not like a text message, IM, or "please return my call" voicemail.

I moved from a company that operated under that paradigm (Slack was the primary mode of internal comms) to one that treats email as the primary mode of comms. It was a minor challenge to start watching my inbox and keep it at zero-unread (something I don't care about at all in my personal emails). Feels natural to me now when I'm in work-mode.