Just don't work for free
Don't work for free.
I used to when I was young, stupid and had no family responsibilities. I don't anymore. I point blank refuse to set up email on my mobile. As far as I am concerned, email isn't urgent anyway and it is something that is strictly viewed in work time.
If something is urgent, call me, but it had better be genuinely urgent. I am available for certain people to call me out of hours in an emergency. I know they won't abuse it so I will answer. I will respond if I am able, but if I am doing family stuff then it will have to wait until I am in a position to help.
If somebody insists you respond on your own time, put in an overtime claim.
If an organisation is depending on people working for free, then they are understaffed and/or badly managed. Either way, that is a problem for management, not you. If you let people abuse you then it will become expected and if there is a staffing issue it won't push them to solve it if everybody else bends over backwards. The management will just crow to their bosses about how efficient they are and get a bonus at your expense.
This is especially the case in a large organisation. When working for small companies, I have been a lot more flexible, but that is because there is a lot more give and take. If I put in extra hours unpaid, I knew I would be able to take time when I wanted it.
Don't work for free!