That's ridiculous. The protection should be to protect the employee who sets their phone/computer not to check email during off hours, not a prohibition on the sender uploading a message to their mail server's queue.
I email my staff at 2am constantly. I don't expect replies until they're "at work" (wherever and whenever that may be).
If someone wishes to volunteer to work 24/7, it isn't my job to stop them. It's insane of them, though, and I might contemplate firing someone who felt pressured to act/respond at 2am (for being dumb and unreasonable).
Just because you think there is no pressure to reply, doesn't mean there isn't a societal/workplace culture that pushes people to do so when their superiors ask for something. Same reason you can tell a co-work something is dumb, but you would say 'lets look it from another angle' to a manager or ceo.
That's usually the case, the above source didn't explain it correctly.
The law actually only obligates the company to agree a set of rules with the staff elected representatives (usually from a union). In almost all cases, those rules are simply that employees cannot be obligated to connect outside their paid work hours, and not suffer any consequence for not connecting.
It is normal to work at 2am if you work the way I and most of my associates work.
I think it's fairly common for hackers and other deep-thinking types to work very intensely for 2-5 minutes at a bunch of different times all throughout the day.
Gaslighting your team could backfire in any number of ways.