Email Subject Lines: Longer subject increases opens 8.2%


Before I get started, please allow me to reiterate something we’ve expressed around here for years: The objective of an email is to get a click. However, while this goal seems clear, your prospective customers aren’t looking for a reason to click your email – they’re looking for a reason to delete it.

In order to capture the interest of someone navigating a cluttered inbox, your subject line message must be clear enough to garner attention and express value. The subject line is really just the first part of an ongoing conversation you’re trying to establish with a prospective customer. These conversations need to operate just as if they were happening in real life.

Think about it. When you begin an in-person conversation, you don’t speak in vague terms and hope someone is listening. Instead, you more than likely introduce your story with a quick, but valuable statement intended to get the audience’s attention, hoping they’ll focus on you and listen to the more elaborate details that follow.

If you succeed, not only do you get to tell your hilarious/heart-wrenching/life-altering story, but you also open the door for further relevant conversation. This practice also needs to be employed in email dialogue, as seen in the experiment below.

Experiment Background

Our Research Partner (anonymized to protect company’s competitive advantage) is a leading international oil field services provider. They develop products, services and solutions that aim to optimize customer performance in a safe and environmentally sound manner. When the company agreed to sponsor a major conference for the International Association of Drilling Contractors (IADC), they developed an email to promote this partnership and help draw interest in the new drilling products and online resource center they were set to unveil at the conference.

Treatment #1 vs. Treatment #2: Shorter isn’t always sweeter

In developing this email (which I’ll cover in more detail in a later blog post) the company was compelled to put as much information as possible into the body copy, effectively negating the value of the subsequent landing page. However, their approach to the email’s subject line was considerably more minimalist:

First Look at New Products, Technology, and More

At first glance, this seems like a simple, effective subject line. The topic is clear enough, and the words “First Look” and “New” all imply a level of exclusivity. However, unless you’ve memorized every email address that graces your inbox each day, there remains some huge questions:

  • Who is this from?
  • Why are they emailing me?

…and most importantly…

  • Exactly what in the blue [heck] is this about?

In a perfect world, recipients of this email would click through to find the information they seek. But as we know, it’s not a perfect world, and this subject line is too vague and generic to capture the requisite interest for opening the email link.

Our research team decided to test the original subject line against a longer, yet more focused alternative:

IADC 2011 – Exclusive First Look at New Products, Technology and More


The treatment subject line generated an 8.2% higher open rate than the control.

While the first subject line may seemingly appeal to a broader range of recipients, the treatment does a much better job of beginning the all-important conversation with potential customers. By opening the subject line with the name of the conference (IADC 2011), the recipient immediately knows what the email content is about (and likely, who it’s from), making the supporting terms “First Look,” “New Products” and “Technology” all the more relevant.

A positive boost came from the term “Exclusive,” which was inserted to add strength to the value statements that followed. While “First Look” lent an air of immediacy to the first subject line, adding “Exclusive” to the treatment created an incentive for the user to take action.

Remember, your subject line needs to open the dialogue and encourage further interaction. Because you have a matter of microseconds to garner enough interest for an open, relevance trumps brevity, no matter what the subject line gurus tell you each day. Though they should be as brief as possible, do not sacrifice relevance to your audience, just to save a few characters.

Related Resources

Crafting an Engaging Email Message (Web Clinic replay)

Internet Marketing for Beginners: Email marketing optimization 101

MarketingExperiments Email Marketing Course

Live optimization with Dr. Flint McGlaughlin at Email Summit 2011 (blog post recap)

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  1. Michael Neece says

    Outstanding advice, succinctly presented and communicated with an example. Bravo!
    Thank you

  2. Matt Minarik says

    I deal a lot in lead generation testing, and have for over 20 years, and I even teach on it, and this is an excellent thought process and approach. The initial paragraph smartly pointed out that the goal of the reader is to delete your e-mail, and that sets the right perspective. Great job.

  3. Trung Ngo says

    This is quite interesting. I have done some email marketing for my old company and it seem to be the shorter subject line will tend to get more click through. I guess it can work either way and depending on the products/services or even the mailing list to see the outcome.

  4. Dave says

    I always worry about how a longer subject line will appear in the recipient’s email window as often the subject line is truncated. I’ve always leaned towards shorter subject lines and making sure the key words I am using are at the beginning.

  5. Janice says

    Short, sweet and something we can apply everyday. Thanks!

  6. Andrew Kordek says


    Good post. However, this is one email and a B2B scenario. Has this one test resonated for the rest of emails that have been sent?

    Andrew Kordek
    Co-Founder, Trendline Interactive
    An email marketing consultancy.
    Twitter: @andrewkordek & @trendlinei

    1. Brad Bortone says

      Great question. This is just one test and should be taken that way. However, with that said, it does resonate with our overall research in some ways.

      For instance, the use of the specific conference name “IADC 2011” in the subject line of the treatment increases the specificity and clarity of the offer, and our overall email research suggests that this will increase the likelihood of customer response. Our research directory ( lists experiment after experiment where this is the case. Our hypothesis is that this clarity and specificity equates to a more appealing and credible expression of the value proposition, and that why people respond to it more.

      However, with that said, it is interesting to note that “IADC 2011” also increases the length of the subject line (as mentioned in the title of this post), so does that mean long subject lines are better than shorter ones? Well, so far our overall research has not indicated that longer subject lines outperform shorter ones in all cases. In this test, longer meant more specific and therefore more clicks, but if the tables were turned and the shorter subject line was just as specific, it might have performed just as well as the treatment. The only way to know for sure is through follow-up testing.

      The overall resonating point that this test makes is that what you put in your subject lines matters. Be specific and clear. This is a principle that resonates across B2B and B2C, email and Web pages, digital to in person, etc.

      Hope that helps. Again thanks for the question.

  7. Richa Gupta says

    I don’t quite agree with you. I believe that it’s not the length of the subject line, but the choice of words that make a difference to the open rate.
    Also, I agree with Trunq on shorter lines working better.

    1. Brad Bortone says


      We agree. What this test told us was that specificity and detail garnered interest. In this case, it led to a lengthier sub line, but if it could have been done more effectively with less words, we would have tested that as well. Ultimately, details meant more to this audience than any other variable.


  8. Stewart Gandolf says

    This results in this article is not surprising to me at all. I hear people saying things like “short subject lines are the way to go,” but when you look a little deeper, that commonly turns out to be opinion. Few people actually test their assumptions. If direct response proves anything to me, common wisdom is commonly wrong.

    Here’s a link on that just in case you think your readers would find that useful – if not strip it out.

  9. Jennifer Woodard says

    I agree that detailed subject lines seem to work better for me even when they are long. I have tested various lengths in the past and may do it again in the future.

    Great article.

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