Always - as long as it makes proper use of paragraphs and doesn't have too many spelling/grammatical errors.
If I ever have to respond to an email asking clarification questions because they wanted to write a concise email, then my time is being wasted.
And it shows. If you are not the boss, you can't just write something and expect the recipient to figure it out.
big tech CEOs and major politicians use email almost as if it's an instant messenger: short, informal, to the point.
I guess it kinda bites them in the ass because the way I know this is via email leaks or subpoenas...
But it does mean that people can use whatever clients they like, and they can be across multiple organisations without weirdly expensive plans and administrators bridging instances or what have you.