Some German company, I believe the Deutsche Post/DHL, was changing their email servers to not deliver emails outside of working hours. Granted this works because all folks are in the same Timezone, but it is such an elegant solution. Just not deliver the mails until the next day. If it is super urgent you can still call. Would be cool if that was a mail client feature.

I have no work mail or chat on my private devices and actually move all incoming mail to a temp imap folder which I don’t sync to my phone or laptop. Then a cron job moves it to my inbox between 8 and 8.