Good preheader text adds something the subject line doesn't say, keeps the important words near the front, and is set on purpose in every email rather than left to whatever your platform grabs. It's earning or costing you opens right now, and most senders treat it as an afterthought.
The preheader (also called preview text) is the snippet of copy that appears beside or below the subject line in the inbox. On mobile, it often takes up more visual space than the subject line itself. It's the second thing your subscriber reads when deciding whether to open your email. Write it well and it extends the persuasive power of your subject line. Ignore it and your ESP pulls the first line of your email body, which is frequently "View this email in your browser" or nothing useful at all.
The fix is straightforward once you understand the mechanics. Here's what works, why it works, and how to set it up in every email you send.
Key takeaways
- Preheader text is the preview line beside or under the subject line, and if you don't set it, the inbox shows whatever text comes first.
- Use it to add a second thought to the subject line, never to repeat it.
- Put the important words in the first 40 to 60 characters, because how much shows varies by inbox and device.
- Avoid all caps, piles of punctuation, misleading promises and hidden keyword stuffing.
- Test it by changing only the preheader, and judge it over several sends, not one.
What Preheader Text Actually Is (and What Most Senders Get Wrong)
Preheader text is technically a hidden line of HTML placed at the very top of your email body, before any visible content. Email clients pick it up and display it in the inbox preview alongside the subject line. If you don't set it deliberately, email clients will surface whatever text comes first in your email, navigation links, legal copy, a broken image alt tag, or an unsubscribe notice.
Most senders get this wrong in one of three ways:
1. They leave it blank. The email client scrapes whatever it finds, which is almost never useful copy.
2. They repeat the subject line verbatim. This wastes the space entirely. You have two distinct impressions to make before the open. Repeating yourself gives you only one.
3. They stuff it with keywords. Preheader text isn't SEO. Subscribers read it. If it sounds like keyword soup, it signals spam, to humans and to filters alike.
Used well, preheader text is a complement to the subject line, not a redundant caption. The operative word is complement.
The Subject Line + Preheader Formula That Works
Think of the subject line and preheader as a two-sentence pitch. The subject line sets the hook. The preheader deepens it, resolves it, or adds urgency.
There are four reliable formulas:
Formula 1, Complete the thought
Subject: The email mistake killing your open rates Preheader: It starts before anyone reads your subject line
The subject line creates curiosity. The preheader extends it without giving away the answer. The subscriber has to open to find out.
Formula 2, Name the benefit
Subject: Your onboarding sequence isn't converting Preheader: Here are the three changes that fix it
The subject line identifies a pain point. The preheader promises a specific payoff. Specific beats vague every time.
Formula 3, Add social proof or urgency
Subject: What [client] changed in their welcome email Preheader: Their sequence, plus what they fixed first
The subject line leads with a result. The preheader signals that the how is inside. This works especially well for case study and results-based emails.
Formula 4, Reframe or contrast
Subject: Stop testing your subject lines Preheader: Test this instead, it moves the needle more
The subject line makes a counterintuitive claim. The preheader offers a redirect. The tension between the two forces the open.
From what I've seen, specific beats vague in subject lines, and the same goes for preview text: the more concrete the promise, the stronger the pull.
Optimal Length and Character Count
Display length varies by email client and device, and Litmus's guide to preview text support shows how much it changes from one inbox to the next. Desktop inboxes generally show more than phones, and notification previews show the least.
The practical recommendation: write your most important content in the first 40-60 characters, then use the remaining space to reinforce or extend. This way the message works even when truncated.
The safest approach is to preview your campaigns in at least Gmail (desktop and mobile) and Apple Mail before sending to your full list.
My working rule is to aim for about 85 to 100 characters total. Short enough to avoid truncation on most devices, long enough to give yourself room to write something meaningful.
Email Preheader Examples Across Different Campaign Types
The formula shifts slightly depending on the type of email you're sending. Here are practical examples across the most common campaign categories.
Newsletter
Subject: What I got wrong about list segmentation Preheader: And the three-question framework that actually works
Promotional / sales email
Subject: The check that changed how I look at deliverability Preheader: Open until Friday, here's what it covers
Welcome email
Subject: Welcome, here's where to start Preheader: One thing to do in the next 10 minutes that makes a difference
Re-engagement
Subject: It has been a while Preheader: Here's what has changed, and what we want to send you next
Case study / results email
Subject: [Real result] in [timeframe], what changed Preheader: The sequence structure behind the result (with the actual copy)
Notice that none of these repeat the subject line. Each one adds a distinct layer of information. That's the minimum standard your preheader text should meet.
How to Implement Preheader Text in Major ESPs
Most email service platforms support dedicated preheader fields, which is always the cleanest implementation. If yours does not, add a hidden element at the top of your HTML template, right after the body tag, with a display:none style. That's the common method, and Litmus's guide shows an example.
For platforms that do offer a dedicated field:
- Mailchimp: Campaign builder includes a "Preview text" field in the Design step
- Klaviyo: "Preview text" field at the top of the email editor
- HubSpot: "Preview text" in the email settings panel
- ActiveCampaign: "Preview text" option within the email editor header
If you're working with a developer or custom template, the implementation is a single hidden element at the top of the body. What matters more than the technical method is making the habit of filling it, deliberately, every time.
Preheader Text and Deliverability: What to Avoid
Preheader text is read by spam filters before it's read by humans. A few patterns consistently trigger flags or damage sender reputation:
All-caps words or excessive punctuation. "OPEN NOW!!!" looks like spam to subscribers, and it's the kind of pattern filters are built to notice.
Misleading preview text. If your preheader promises something the email doesn't deliver, you train subscribers to distrust future opens. That erodes your sender reputation over time. Trust is the underlying asset everything else is built on.
Invisible-text keyword stuffing. Some senders attempt to hide a long string of keywords after the visible preheader using white text. It's a classic spam pattern, and it can get campaigns flagged.
Emoji overuse. One relevant emoji can add visual differentiation in the inbox. Three or more in the preheader reads as noise, especially to a professional audience.
The straightforward standard: write preheader text you would be comfortable reading aloud to your subscriber. If it would sound like spam, it will be treated like spam.
Testing Preheader Text: What to Measure and How
Preheader text is one of the most testable elements in email marketing because it affects only one metric directly: open rate. This makes it easy to isolate.
A practical A/B test structure:
- Variable: Preheader text only (subject line identical for both variants)
- List split: 50/50, and I'd want at least 1,000 recipients per variant before reading much into it
- Primary metric: Open rate
- Secondary metric: Click rate (to detect if preheader tone creates mismatched expectations)
- Run time: Send at the same time on the same day, evaluate after 24 hours
Test one formula type at a time. For example, run "complete the thought" against "name the benefit" for the same subject line. Once you find which formula your audience responds to, use it as your default and refine from there.
I'd track preheader tests over at least three sends before drawing conclusions, because a single test can be influenced by send timing, subject line strength, or segment behaviour. The pattern across multiple sends is more informative than any single data point.
For a broader look at the elements that drive opens before any subscriber reaches your body copy, see our guide to subject lines that get opened. Preheader and subject line strategy are most effective when developed together. If you'd like someone writing both every week, in your voice, that's part of our newsletter management work.
FAQ
How long should preheader text be?
Write your core message in the first 40-60 characters so it survives truncation on mobile. 85-100 characters total is a reliable working length for most send environments. Desktop clients typically display more, but mobile renders what matters first.
Should preheader text always relate directly to the subject line?
Yes, but it should add information rather than repeat it. The subject line earns attention. The preheader should deepen curiosity, name a specific benefit, or add a detail that makes the open feel worthwhile. Restating the subject line wastes one of two impressions you get before the click.
Does preheader text affect deliverability?
Indirectly, yes. Preheader text is scanned by spam filters along with the rest of your visible and hidden copy. Aggressive punctuation, misleading promises, or hidden keyword stuffing can contribute to inbox placement issues. More importantly, preheader text affects whether people open, and how people engage with your email is part of how inbox providers judge your sender reputation over time.
What happens if I don't set preheader text?
Your email client will surface the first readable text in your email body. Depending on your template structure, this could be "View this email in your browser," an unsubscribe line, navigation link text, or broken image alt copy. None of these help your open rate.
Can I use emoji in preheader text?
Sparingly. A single relevant emoji can add visual interest in the inbox. More than one or two tends to read as noise, especially to a professional audience. Test it rather than assume.
Read Next
- How to Write Subject Lines That Actually Get Opened, the mechanics behind what earns the click, from curiosity to self-interest