We reportedly spend a third of our workdays reading and sending emails. And that doesn't count the time we spend biting our nails impatiently waiting for responses to important ones.

We've all been there. Hitting refresh every few minutes so we'll instantly know if we've landed that job, secured that investment, or been accepted into that program.

But what if you never get a response? It might be time to clean up your email-writing act. One simple switch you can make is to change your email sign-off. Ending your emails with this one word vastly improves your response rate. But that's not all. The data scientists at Boomerang have a few more data-backed suggestions to bump up those responses.

Boomerang is a plug-in that will let you know if an email goes unanswered after a certain period of time. In 2016, their customers used the plug-in's reminder feature on over 40 million emails. At the end of the year, Boomerang dug into their user data to determine what the most effective emails had in common. Here are a few of the many insights they found.

1. Lure 'em in with the subject line

David Ogilvy, regarded as the father of advertising, famously said of headlines: "On the average, five times as many people read the headline as read the body copy."

Think of your email subject line as your headline. If it doesn't catch your recipient's attention, they have no reason to open your email. And if they never open it, you're certainly not going to get a response.

Length is key. Boomerang found the shorter your subject lines, the better. "Subject lines with only 3-4 words (excluding email conventions like Re: and Fwd:) received the most responses," the company says.

During both his presidential campaigns, no one knew this sweet spot of subject line length better than Barack Obama. This graphic from New York magazine shows a snapshot of some of Obama's emails during his reelection campaign. Many of the subject lines were simply "Hey," or even "Hey again." Others included "This is critical," "Not going to happen," and "Are you in?"

Think you might catch people's attention by skipping the subject line altogether? Bad move. Boomerang found only 14 percent of (no subject) emails received a response.

2. Follow the Goldilocks rule

No one wants to open an email and be hit with a novel. The shorter the better, right? Not necessarily. Boomerang found that too-short emails were just as ineffective as too-long ones. There's a just-right length for emails that are the most likely to get a response.

"The sweet spot for email length is between 50-125 words, all of which yielded response rates above 50 percent," Boomerang says. Also consider how the person on the other end will receive your email. You might be typing it on a computer, but they could be checking emails on-the-go on their phone. Emails that appear short on a desktop screen look much longer on a palm-sized mobile screen.

Of course, no one is going to count the number of words in every single email they send. So Boomerang offers this rule of thumb for gauging length: A 50-word email is about two short paragraphs. A 125-word email is two normal-length paragraphs and one short one.

The paragraph above is just shy of 50 words.

3. Ask a question (or three)

One of the easiest ways to entice recipients to respond is to ask them a question. Boomerang found that emails containing one to three questions were 50 percent more likely to receive responses than question-less emails.

But go easy on those question marks. Going overboard with the questions is not recommended. Ask more than three, and Boomerang started to see response rates decline. If you've got a slew of questions for this person, email might not be the best channel for finding answers. Consider the old-fashioned talking on the phone method or even scheduling a face-to-face meeting.