FWIW, I found that my XH used email contact to do all sorts of horrid stuff related to kids and money.
He used it to make demands - that were so outrageous that he probably couldn't do it face-to-face - and used it also to establish some sort of 'record' for later (court) use (this was his way of creating a 'reality' that served his own purpose).
None of the email contact I receive from him is pleasant, nor does it represent any sort of small step forward.
Unlike you, though, I don't have the courage to block him. Or maybe i just fear what would follow - he doesn't take well to being thwarted.
At this stage, he uses email to spew and is relatively pleasant face-to-face, most of the time.
IDK whether stopping ALL contact is a good thing or not. OTOH, it shows them the reality of their choice: we are out of their lives.
OTOH, it does not keep the path home paved and smooth; we are not the 'lighthouse' if they can't see our beacon of light.
Does it have to be all or nothing?
That is, could you accept contact - say, if he phoned you up - and speak to him for as long as he was civil? I was going to say as long as he was 'reasonable', but that would not work at all!
