Email preview text checker: see your subject and preheader in Gmail, Outlook and iPhone
Preview text, or preheader text, is the grey line an inbox shows after the subject. Mail apps take it from the first text in the email, so you set it with a hidden preheader at the top of the HTML. Type both here to see roughly where Gmail, Outlook and iPhone Mail cut them.
Or paste your email's HTML to see what the inbox will pick up
Runs in your browser. Takes the first text in the body, hidden preheader included.
Sample result
This 110-character preview text gets cut off on all four inbox mock-ups.
- Preview text
- 110 characters
- Gmail app on a phone
- 41 shown
- Apple Mail on iPhone
- 93 shown
What this means for you
Lead with the key point in the first 41 characters, all a phone's Gmail app shows here.
- Four inbox mock-ups at fixed widths
- Subject and preview characters shown
- Reads the preview from pasted HTML
- Hidden preheader snippet to copy
- Preheader
- Inbox preview
- Truncation
By SimpleVerifier Team · Last updated · Runs in your browser; nothing you paste is sent to us
How do I check my email's preview text?
- Type the from name, subject line and preview text, or press Try an example.
- Read the four simulated inbox rows: Gmail on a computer, the Gmail phone app, Outlook's message list and Apple Mail on iPhone. Each shows where the subject and preview get cut at a typical width.
- Have the email already? Paste its HTML under the second option to see the text an inbox will actually pick up, hidden preheader included.
- Copy the hidden preheader HTML, with a spacer that stops body text trailing in, and paste it right after the opening body tag.
Example
- You enter
- A 32-character subject line and a 110-character preview text.
- You get
- The subject shows in full, but the preview is cut on all four inbox mock-ups: 41 characters show in the Gmail phone app and 93 in Apple Mail on iPhone.
- Limits
- No limit; widths are approximate. Runs in your browser.
What is preheader text in an email?
Preheader text is the snippet that follows the subject line in the inbox list, also called preview text. There is no header field for it: mail apps take the first text they find in the message body. So whatever comes first in your HTML, a "View in browser" link, an image's alt text or a navigation menu, becomes the preview unless you put a hidden line there on purpose.
That hidden line is the preheader: a short div at the very top of the body, styled display:none and max-height:0 so it shows in the inbox but not in the opened email. Many email tools have a preview text field that inserts it for you.
How long should preheader text be?
Write it to be read in the first few words, and long enough to fill the space. No provider publishes a character limit, because inboxes cut by pixel width, not characters: a phone shows one or two short lines, Gmail on a wide monitor shows much more after the subject. The rows above give approximate counts for typical widths, which is a better guide than a fixed number.
If the preview text is shorter than the space, the app keeps reading into the email body. The fix is a spacer of invisible characters after the preheader (͏‌ repeated), which the copied snippet includes.
Is preheader the same as preview text?
Yes, in practice. Preview text is what the reader sees; preheader is the hidden HTML you write to control it. Mailchimp, Klaviyo and HubSpot call the field preview text, and builders' templates often call the element a preheader.
Readers can change how much preview they see. Apple's guide to checking email on iPhone says Mail shows two lines by default and up to five; classic Outlook shows one to three lines, set in how the message list is displayed, and some readers hide it entirely; Gmail's inbox density settings change the row layout too.
How do I add preheader text in Outlook or Gmail?
You don't set it in the mail app; you set it in the email. Outlook and Gmail have no preview text field when you compose a message, so a plain email's preview is simply its first line. For HTML campaigns, use your email platform's preview text field, or paste the copied preheader HTML directly after <body> in your template.
To see how it renders, send yourself a test and check it on a phone and a computer. The simulation here is quicker for drafting, but only a real inbox shows the exact cut.
Preview text field vs hidden preheader vs nothing
| Platform's preview text field | Hidden preheader HTML | Nothing set | |
|---|---|---|---|
| What the inbox shows | Your line | Your line | First text in the email |
| Body text trailing in | Depends on the platform | Stopped by the spacer | Yes |
| Works in any sending tool | Only that platform | Yes | n/a |
Who uses this tool, and for what?
- Email marketers
- Draft the subject and preview text together and see where both get cut on a phone before the campaign goes out.
- Cold emailers
- Check that a plain-text first line reads well as the preview, since cold emails rarely carry a preheader.
- Developers
- Paste a template's HTML and catch a "View in browser" link or alt text leaking into the inbox preview.
- Agencies
- Show a client roughly how a subject line will look in Gmail, Outlook and iPhone Mail before they sign off.
What can’t this tool tell you?
- The rows are simulations at fixed widths with standard fonts, not screenshots of real apps; real truncation moves with screen size, font and settings.
- Readers can show more or fewer preview lines, or none at all.
- Gmail's promotions tab annotations can change what the row shows; this doesn't model them.
- Reading the preview from HTML follows document order; an app that skips hidden text may show something else.
Common questions
- What is preheader text?
- The line of text an inbox shows after the subject. Apps take it from the first text in the email body, so senders put a hidden preheader at the top of the HTML to control it.
- What does preheader text do?
- It gives the reader a second line, after the subject, to decide whether to open. Without one, the inbox shows whatever text comes first in your email.
- How long should preheader text be?
- There's no fixed limit; inboxes cut by pixel width. Put the point in the first few words and make it long enough to fill a desktop row, adding a spacer so body text doesn't trail in.
- How many characters should email preview text be?
- Phones show roughly one or two short lines and desktop Gmail shows more after the subject. Check the counts in the simulation above rather than relying on one number.
- Is preheader the same as preview text?
- Yes. Preview text is what readers see in the inbox; the preheader is the hidden HTML element that sets it.
- How do I add preheader text to an email in HTML?
- Put a hidden div right after the opening body tag, styled display:none and max-height:0, containing your preview text. The tool above writes it for you, with a spacer.
- How do I see preheader text in Outlook?
- Turn on message preview in the View tab. Classic Outlook shows one to three lines under Message Preview; new Outlook has a Show preview text option.
Sources
Authentication and capacity are half of deliverability.
The other half is who you send to. Every hard bounce counts against the domain and inboxes you are sending from, and nothing in DNS can tell you which addresses on your list are dead.
- Bulk verification with real SMTP mailbox checks
- Hard bounces removed before a send, not discovered after
- Catch-all, disposable and role detection on every row
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