Boomerang's Respondable widget that you can download right into your browser to be used within Gmail. Its aim? To help you craft better emails that improve your response rates. Using machine learning algorithms that improve based on how you pen your various emails to different recipients, it uses that intelligence to assist you when it comes to how you write your messages.

When you activate Boomerang, you get a new bar inserted into the window you use to compose messages that will change in real-time depending on what you write. Clicking on it brings up a new menu that offers suggestions based on the text in the window. Subject length, word count, question count, and reading level are available for free users, with positivity, politeness, and subjectivity measurements available for anyone who springs for the Advanced Features options.

I put Boomerang Respondable to the test and it did a decent job of measuring the message I sent to a willing Engadget guinea pig. I kept it short to a few paragraphs, asked one question, and kept my subject line to a reasonable length. With a few tweaks I was able to swing the "response" meter to "likely," which was in the green zone. I didn't reach "Very likely," which is a cool teal that I feel a little disappointed I didn't try enough to reach.

Respondable is an interesting tool that could absolutely help you compose better emails, but I also wonder how well these algorithms actually work. I'm going to be utilizing it to see if I start to get responses in a more dependable manner.

If you're interested in trying out the free version, you can get it for both Gmail and Outlook.