Which Subject Lines Work Best?

Subject Line QuestionsBecause its human nature to try to answer questions, using a question in the subject line of an email is a great way to engage and hook your reader, so increasing your open rate.

However, just asking any question is not enough to increase your email open rate. It needs to be the right type of question, one that intrigues the reader enough to open, with the expectation of finding the answer.

With the help of a selection of strong performing real subject lines I’m going to give you some principles to creating questions that intrigue and motivate readers to open your email.

Top performers from three B2C brands

The following subject line pairs are real campaign subject lines from three B2C brands. Each pair has one subject line that delivered a top open rate for the brand and one with a low open rate (subject lines provided courtesy of Phrasee).

Brand 1

  • Top performer: Fancy some [product] for the weekend?
  • Poor performer: How does [brand] make great [product] even better?

The bottom performer was not a question of interest to most of the customers. It focusses on the brand and its products, not the customer.

Bob Bly, author of The Copywriter’s handbook’, says a good question is one “the reader can empathise with or would like to see answered”. The poor performer doesn’t do this.

The top performer delivered 44% higher clicks, according to the subject line performance prediction tool Touchstone.

Brand 2

  • Top performer: We Have a Winner! Is It You?
  • Poor performer: What’s Trending This Christmas? [product]!

Really strong questions are ones that the reader can’t answer without opening the email.

The top performer here is clever since it asks a question the reader definitely would like to see answered and one that is impossible for them to answer without opening. In fact Touchstone puts the click rate of the top performer a whopping 78% above the industry average.

There is more than one way of posing a question the reader can’t answer; I’ll come to that a bit later.

The poor performer asked a question customers might wish to see answered, but is spoilt by the marketer answering the question themselves, thus effectively negating most of the value of asking the question in the first place.

Brand 3

  • Top performer: £5 off your next order, [first name]? We’ve just added something special to our sale
  • Poor performer: Kids moving out? Stock them up with essential [product]

The poor performer is a closed question. The effect is that everyone who doesn’t have kids moving out will say “no” and hit delete as being not relevant. It might have been better to focus the question on why the product is essential.

In Cialdini’s1984 bestseller “Influence: the Psychology of Persuasion”, one of his six principles is that of consistency.

Humans are consistent with previous choices, so if someone nods and agrees with a yes to a subject line, then they are more likely to continue agreeing with you as you expand on your question in your body copy.

So when using closed questions, make sure the answer is ‘yes’ for the target audience.

901 subject lines, guess which won?

Marketing Experiments ran a subject line contest amongst their audience of marketers. They asked for subject lines to test. From the 901 suggestions received they used their experience to pick the best 6 and then ran a split test of these.

With 901 to pick from the six were no lame ducks. The winner scored 125.9% click uplift against the weakest of the six.

The six subject lines tested were

  • Quarterbacks aren’t the only changes being tested in Denver
  • A scientific way to increase your conversions
  • Do your landing pages pass this test?
  • [Optimization Summit] 3 Days to a Better Website ($300 Off Coupon Inside!)
  • Learn 3 tips that made that made 10,000 landing pages extremely successful
  • Optimization Summit 2012 – Speakers List Now Up! + Save $300 Today

The winning line was the question based subject line “Do your landing pages pass this test?”. This question is powerful because:

  • Whilst it’s a closed question, the reader can’t answer without opening the email
  • It appeals to the target audience, people interested in improving landing page performance
  • It plays to loss aversion, triggering a concern that your landing pages could be failing a simple test

Closed questions used correctly are powerful but don’t miss out on using open questions too. If you’ve ever heard advice on how to start a conversation or what makes a great chat up line the answer is to use open questions not closed.

Open questions are invariably impossible for the reader to answer without opening your email. Strike a nerve with the open question and the open will follow.

Drayton uses questions in 30% of his subject lines

Drayton Bird has written more great copy than most, including for a string of major brands and at agencies such as Ogilvy. In a 2014 DMA survey of 433 copywriters Drayton was rated one of the top five copywriters (see page 36 of the copywriter’s consensus findings).

Analysis of Drayton’s emails from the last 3 years shows he uses questions a huge 30% of the time. He obviously believes in questions when promoting his services.

When the subject line and email performs well he even re-uses them. Why waste good work? Here are some examples of his repeated strong performers.

  • Could this crazy estate agent improve your copy?
  • Do you agree with this?
  • How Good Is Your Gut Instinct?
  • Run your own business?
  • Want to coin it this year? Copy this man
  • What if your mother was blind?
  • What Makes A Good Slogan?
  • What’s wrong with this picture?
  • Where is the money you are praying for?
  • Would you do what Ogilvy did?
  • You Have A Brand – Why Throw It Away?
  • You thought I was kidding?

Notice how he uses open and closed questions. Even many of the closed questions leave you needing to open the email to answer the question.

“Want to coin it this year? Copy this man”. Of course the answer to the question is yes. And “Copy this man” is specific, implying there is a simple answer as to how. Remember Cialdini’s consistency principle. Once you’ve said yes you’re nodding along nicely.

“Would you do what Ogilvy did?” could have so easily be a statement about what he did but by posing the question it’s far more engaging and teases into opening the email.

“What makes a good slogan?” appeals directly to Drayton’s target audience. It’s an open question they will have and want answered.

“How good is your gut instinct?” is closed in nature, but because no-one can answer it with certainty it breeds fear, the concern your instinct is not as good as it should be.

I asked Drayton about subject lines and he gave this sage advice…

“Surprisingly few people realise that what makes for a good subject line is very similar to what makes for a good headline. Media change. People don’t. The most significant difference to me is that curiosity seems to matter more in subject lines than in headlines”


How could you make use of questions in your subject lines? Just remember these principles:

  • Use a question the with which the reader empathises
  • Look for question your reader would like to see answered
  • Focus on questions that can’t be answered without opening the email
  • When asking closed questions make the only reasonable answer one of ‘yes’. Get your reader nodding from the start

As with all tactics don’t overdo it and only use questions. The best strategy to keeping your subject lines engaging is to make them fresh and varied. Take a look at nine more split tested subject lines for more inspiration.

Acknowledgements; My thanks to Phrasee for providing brand subject lines from their database of subject line results and Touchstone Subject Line Gold for prediction of the best subject lines.

Plus Drayton Bird for allowing me to use his subject lines as examples. Drayton literally pours out continuous sound and proven marketing advice. Better still he’s genuine. He’ll happily tell you about his costly failures, so you might avoid them, as well as his astounding successes. Take a look at draytonbird.com.