Boomerang's study has concluded that 75 to 100 words get the best response rates. For most emails. five sentences are all you need. If you need more, it might be a sign to call for efficiency.
There might be questions and requests you have, but the longer your message does not necessary turn to the result.
Focus on having one clearly stated goal for each email.
What it is you want? Why they should give it to you? When do you need it by?
Tailoring the small talk