I turned off email notifications on my phone a long time ago and it is lovely. I don't think about checking work email when it's outside of work hours. Certain clients have my cell number and they may call or text but even they usually decide to send an email and wait for a response.

It's rough, though. I take upset/disappointed clients personally and will lose sleep even if it's not our fault, outside of business hours, etc. It just sucks when there's a problem - period.