Warning: this only applies to regular office workers, not management or freelancers.
Are you getting paid for checking company emails after working hours? You are not, right? How is offering your limited, private time FOR FREE to a company worth it? Is your private life SO boring, you need to do something that many of us do not even like doing during office hours? Are you afraid to be the only one in your team to bring some sanity? Do you think your boss is going to respect you less if you put clear boundaries between work and private life? Do you think you might lose your job if you don't check emails at all hours? Might be time to start looking for a new job...
I know, this post is a bit on the rough side, but I'm just trying to challenge the status quo for some people. I have personally met a lot of good, nice people who would think that they MUST do stuff for the company for free, after hours. Without any good reason. Actually, I had this one colleague who would check emails even very late at night, and if there was someone reporting a bug would jump in and try to fix it. And guess what? Countless times his code was really bad and it caused many more issues than it intended to solve in the first place.