It is proper Netiquette to be concise. Don't write long messages.
Many people do not read an entire email message for various reasons. The internet demands immediacy. Some users do not read entire email messages because they are delivered to their smartphones others may not think they have time to read an entire message.
Whatever the reason, many users do not read an entire email message, so it’s good netiquette to compose short messages.
Write short messages because people do not read an entire message when it is long.