Split Testing Short vs Long Form Email Content

What Counts as Short vs. Long

Short-form emails typically contain 50 to 150 words: a brief intro, a clear value proposition, and a single call to action. They take less than 30 seconds to read and are designed to drive an immediate click. Long-form emails run 300 to 800 words or more: they tell a story, build a case, address objections, and provide enough information that the reader can make a decision without clicking through to another page.

Both approaches have loyal advocates, which is precisely why you should test rather than commit to either format based on opinion. The right answer for your audience might be different from what works for your competitor's audience, and it might vary by campaign type.

When Short-Form Tends to Win

Short emails typically perform better when the recipient already knows your brand well, when the offer is simple and easy to understand, when the call to action is low-commitment (click to read an article, visit a page), and when the email is one of many the person receives from you. Regular subscribers who get weekly emails from you have already been educated about your brand. They do not need a long preamble. They want to know what is new and what to do about it.

Short emails also tend to perform better on mobile devices, which now account for the majority of email opens. A short email displays entirely on the screen without scrolling, putting the CTA within immediate reach. A long email requires scrolling and sustained attention, which mobile users are less likely to give.

When Long-Form Tends to Win

Long emails typically perform better when the offer requires explanation, when the commitment you are asking for is significant (purchasing a product, booking a demo, starting a subscription), when the reader is new to your brand and needs to build trust, and when your content itself is the product (newsletters, educational content, storytelling).

Cold outreach emails are a notable exception where both lengths can work. A short, direct cold email respects the recipient's time and gets to the point. A longer cold email that tells a relevant story or shares a specific insight can build enough credibility to earn a reply. Test both for your outreach campaigns rather than defaulting to either approach.

How to Structure the Test

For a clean short vs. long test, keep the subject line, sender name, and send time identical. The only difference should be the email body content. The short version should contain the core message distilled to its essential elements. The long version should expand on that same core message with additional context, evidence, examples, or storytelling. Both versions should have the same CTA linking to the same destination.

Measure click-through rate as your primary metric rather than open rate, since both versions have the same subject line and should produce similar open rates. Also measure the downstream conversion rate: how many people who clicked through actually completed the desired action. A long email might produce fewer clicks but higher conversion per click if it pre-qualified readers before they clicked.

The Hybrid Approach

Many successful email programs do not commit to one format. They use short emails for promotions, announcements, and re-engagement, and long emails for educational content, case studies, and high-consideration offers. Test to find which format works best for each campaign type, then apply the right format to the right situation.

You can also test a hybrid format: a short teaser email that gives just enough information to generate curiosity, with a "read more" link to a full article or landing page. Compare this against a long email that contains all the information within the email itself. Some audiences prefer to consume content in the email; others prefer to click through to a dedicated page.