Should You Capitalize Your Subject Lines? This Marketing Expert Found Out

Discover the simple strategy that increased both opens and clicks.

Have you ever wondered if you’re using the right tactics to market your business?

John Oszajca did. He’s the founder of Music Marketing Manifesto, an online consulting business that teaches musicians how to sell and promote their music.

Oszajca has been capitalizing the first letter of his email subject lines for years. Yet, he wondered whether this was giving him the highest opens and clicks possible.

So he used a simple tactic to find out.

The simple subject line split test Oszajca used to get more people to open and click his emails.

To test his assumptions about subject lines, Oszajca set up an email split test.

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He created two identical versions of a promotional email for his upcoming “Copywriting for Musicians Workshop.” Both versions warn subscribers that this is their last chance to register for the workshop. In his first email, he followed his typical formula of capitalizing the first letter of his subject line. He also capitalized the first letter in the second clause.

Subject line #1: Last chance – This ends tonight

In his second email, he didn’t capitalize any letters.

Subject line #2: last chance – this ends tonight

He sent each email to a different 10% of his subscriber list.

To capitalize a subject line or not? The answer is below.

After waiting 4 hours, Oszajca’s split test results revealed that the subject line with lowercase letters got 35% more opens and clicks!

So he sent the winning email to the remaining 80% of the subscribers on his list.

“It was fun to test certain things that I have been doing for years based on gut,”  Oszajca says. But now he has data to back up his process, he says, and a deeper understanding of his subscribers’ behavior.

Related: 6 Email Split Tests You Can Set Up in 1 Minute

Now, find out what your own audience prefers!

Want to know what kind of emails lead to the best performance with your own subscribers? Use AWeber’s split testing feature to find out. (Don’t have AWeber? Claim a 30-day free trial here.)

And if you’d like to learn more about split testing, download our FREE guide to split testing.


  1. John Homer

    10/25/2018 2:47 pm

    Just wondering … The article stated he waited 4 hours to review his results. Was the 4 hour time span long enough to collect enough responses [the N] to give him statistical significance of his data?

  2. Liz Willits

    10/26/2018 11:48 am

    Hi John,

    Great question! If your email list is large enough, 4 hours can definitely be enough time to get statistical significance. For this business, that was the case. However, if you’re working with a smaller email list, it’s probably best to wait 24 to 48 hours to choose a winner.

    Thanks for reading!

  3. Danielle

    10/26/2018 2:01 pm

    I’m curious about why lower-case won out. But that would obviously require more in-depth surveying/analysis of the audience. It’s interesting because when I see lower-case, my mind automatically categorizes it as spam. My first thought is, oh, just another illiterate get-rich-quick-schemer. Plus, for me, lines that aren’t capitalized or punctuated properly are harder to read, which makes them an annoyance.

    Any idea or insight on why all lower case got a better response?

  4. Liz Willits

    11/2/2018 2:16 pm

    Hi Danielle,

    Thanks for reading! I think the lowercase sentence won because it stands out from other emails in the inbox. Many people capitalize the first letter of their subject lines or the first letter of every word. By not capitalizing at all, you stand out from the norm, which may increase opens. That’s my guess. However, it’s worth testing this with your own audience to see if they react the same way.