I've had some success with sending email that has a short and long version (or if you include the subject itself, 3 levels). Ask your main question in the first sentence or two, enough to provide context, detail, and what you want.
At the end say "[more detail below if needed]". Draw a line in the email ===== and include more detail below that they can dip into if necessary.
I do this too, especially when emailing people who I believe are unable or unwilling to read a long email. It feels weird and unnatural. I'm not sure if the people I'm sending to appreciate it, but I know I can very easily become very verbose, and which details are important is very context sensitive and sometimes non-obvious.
At the end say "[more detail below if needed]". Draw a line in the email ===== and include more detail below that they can dip into if necessary.