There are some people who hate writing so much that their emails are only ever a paragraph or so long. There are others who are so prolific that their emails go on for pages. It's probably best to find something in between.

If you are a writer who tends to go on and on, you have to remember that people are very busy. They often don't have time to read long emails. On the other hand, you're probably not providing much value or making enough of an effort if your emails are too short.

Find a happy medium, and your response rates will likely improve.

You can approach this from a “hybrid” perspective:

1. Give your readers who open your emails but don't have a lot of time reading them an opportunity right up front in the email to take whatever action you want them to take: “Click here for the full skinny” or “Click here to cut to the chase.” You can also bold the important parts and use bullets for especially important information.
2. For those who love reading your voluminous emails, give it to them.

This method works pretty well.