Email preview text is the snippet of message content the inbox displays beside or beneath the subject line, and it is written in a hidden field rather than pulled from the visible email body. It is also called preheader text.
Left unset, the inbox takes whatever text appears first in the message — frequently "View this email in your browser" or an unsubscribe line. That is prime inbox space spent on nothing.
What preview text does
The inbox row a subscriber scans contains three fields, and preview text is the third.
| Field | Its job |
|---|---|
| Sender name | Establishes who this is from |
| Subject line | Creates the reason to open |
| Preview text | Extends the reason, or confirms it |
Preview text is the only one of the three that most senders leave to chance. It occupies roughly as much visual space as the subject line in most clients, and on mobile it frequently occupies more.
The full picture of how these three fields work together is in email copywriting: emails people actually read.
How long email preview text should be
Display length varies by client, device, and whether the reading pane is open, so no single number is correct everywhere.
| Context | Approximate visible length |
|---|---|
| Mobile, most clients | 35–90 characters |
| Desktop, list view | 55–100 characters |
| Desktop with reading pane | Often shorter, sometimes none at all |
Write the essential meaning into the first 40 characters and let the rest be a bonus. A preview line whose point lands at character 85 works on a laptop and fails on every phone.
Some clients display nothing at all, which is the argument against ever putting essential information there and only there.
The four ways to write preview text
Each one suits a different email, and choosing deliberately is most of the work.
1. Extend the subject line
The strongest default. The subject line opens a thought and the preview text continues it, so the two read as one sentence.
- Subject: The paragraph I deleted from every email
- Preview: It was costing us about a third of our clicks.
2. Add the specific detail the subject line left out
Useful when the subject line is short and intriguing and the reader needs one concrete fact to justify the open.
- Subject: Your Q3 email calendar
- Preview: Twelve sends, mapped week by week, with the copy briefs attached.
3. Answer the objection
Suits promotional email, where the most common reason for skipping is a predicted catch.
- Subject: The August cohort opens tomorrow
- Preview: Same price as last time, and the recordings are included.
4. Ask the question the email answers
Works for educational and diagnostic email, where the reader recognises their own problem in the question.
- Subject: Why nobody clicks your emails
- Preview: Six causes, and a five-minute way to find out which one is yours.
Three mistakes that waste the field
Repeating the subject line. Duplication uses the space to say something the reader has already read, which converts a second headline into wasted pixels.
Leaving it blank. The client fills it with the first text in the message, which is usually a browser-view link, an unsubscribe line, or a preheader table full of formatting artefacts.
Filling it with the whole first sentence. A preview line cut mid-word at character 42 reads as sloppy and signals that nobody set it deliberately.
How to set preview text in your platform
The field exists in every major sending platform, under a name that varies.
| Platform | Where the field lives |
|---|---|
| Klaviyo | Preview text, on the campaign content step |
| Mailchimp | Preview text, beneath the subject line field |
| ConvertKit (Kit) | Preview text, in the broadcast settings |
| MailerLite | Preview text, on the campaign setup step |
| Brevo | Preview text, in campaign settings |
| Campaign templates in code | A hidden <div> at the top of the body, styled display:none; max-height:0; overflow:hidden; |
Hand-coded templates need the hidden-div method plus a run of non-breaking space entities after the text, which stops the client pulling body copy in behind a short preview line. Without the padding, a 40-character preview line is followed by the first 60 characters of the email, which is the artefact that produces "…View in browser · Unsubscribe" in the inbox.
Testing preview text honestly
Preview text is testable, with two caveats that apply to any open-rate test.
Apple's Mail Privacy Protection inflates reported opens, which makes open rate a noisy metric for a test whose whole effect is on opens. Where the email has a single clear action, click rate is the steadier judge.
The effect size is small. Preview text is a refinement rather than a lever, and detecting a real difference needs a large segment and several repetitions. The reason to write it well is that it costs one line and is currently producing nothing.
Testing methodology, and how to avoid drawing conclusions the data does not support, is in email subject line formulas.
What's in the book, not here. The per-client character-limit table and 15 before-and-after rewrites are in The Email Copywriting Playbook.
Frequently asked questions
How long should email preview text be?
Visible length runs roughly 35 to 90 characters on mobile and 55 to 100 on desktop, varying by client and reading-pane setting. Write the essential meaning into the first 40 characters, because a line whose point lands at character 85 fails on every phone.
What happens if you leave preview text blank?
The inbox pulls whatever text appears first in the message, which is usually a browser-view link, an unsubscribe line, or formatting artefacts from the template. That is why so many inbox rows read "View this email in your browser".
Should preview text repeat the subject line?
No. Duplication uses the space to say something the reader has already read. The strongest default is to extend the subject line so the two read as one continuous sentence.
What is the difference between preview text and preheader text?
They are two names for the same field — the snippet the inbox displays beside or beneath the subject line. Sending platforms use both terms, and hand-coded templates implement it as a hidden div at the top of the body.
Does preview text affect deliverability?
Not directly. Preview text influences whether a message is opened, and opens contribute to engagement, which contributes to sender reputation over time. The wording itself is not a filtering signal.
How do I add preview text to a hand-coded email template?
Place a hidden div at the top of the body styled with display:none; max-height:0; overflow:hidden;, containing the preview text followed by a run of non-breaking space entities. The padding stops the client pulling body copy in behind a short preview line.
Do all email clients show preview text?
No. Display varies by client, device, and reading-pane setting, and some contexts show none at all. Essential information should therefore never live only in the preview text.
What to do next
Open your last campaign in an inbox and read the preview text as it actually rendered. If it says "View this email in your browser", the field was never set.
Then write one line for your next send that continues the subject line rather than repeating it, and keep the meaning inside the first 40 characters.
Free: The Subject Line & CTA Swipe File — the lines worth stealing, with notes on when each one fits.
Go deeper: The Email Copywriting Playbook — the per-client character-limit table and 15 before-and-after rewrites.
Related guides
- Email copywriting: emails people actually read — the complete system
- Email subject line formulas — the field this one extends
- Why nobody clicks your emails — the next stage after the open
- How to stay out of the Gmail Promotions tab — how the inbox row is categorised
- Email marketing benchmarks by industry — judging whether opens are actually low
Free: The 60-Minute Email Authentication Fix
A no-fluff checklist to set up SPF, DKIM & DMARC correctly and pass Gmail & Yahoo's sender requirements.
Muhammad Basim has worked in digital marketing since 2013, focused on email deliverability and AI-assisted content production. He is the author of the Email Deliverability Playbook and the Email Copywriting Playbook, and has run 100+ email campaigns for ecommerce brands, coaches, and B2B senders. He writes about email, SEO, WordPress, and AI — with a bias toward what can be tested over what sounds good.
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