What is the preheader?
The preheader (also called preview text) is the short snippet of text that appears next to or below the subject line in the email inbox. It's the text that email clients pull from the beginning of the email body to give recipients a preview of the content.
In Gmail's inbox on desktop, you see it as gray text after the subject line. On mobile, it often appears on a second line below the sender name and subject. In Apple Mail, it shows as a second line in the message list.
It's one of three visible elements in the inbox alongside your sender name and subject line — and it's often underused.
Why preheaders matter
Open rate is determined by the combination of sender name, subject line, and preheader working together. Recipients scan all three before deciding to open.
A preheader that extends or adds to the subject line gives the recipient more reason to open. A preheader that's empty, or that shows "View this email in your browser" or "Having trouble viewing?" is wasted space.
How email clients generate preview text
If you don't specify a preheader, the email client pulls text from the beginning of your email. Often this means:
- Your logo's alt text ("Company Logo")
- "View in browser" link text
- A navigation bar
- Whatever your first visible paragraph is
None of these are compelling. Take control of this text explicitly.
How to write a good preheader
Extend the subject line, don't repeat it. The subject and preheader are read together. Use the preheader to add information the subject couldn't fit.
Subject: Your order has shipped
Preheader: Arriving by Thursday — track your package inside.
Add urgency or specificity. If the subject creates intrigue, the preheader can pay it off or deepen it.
Subject: Last chance on this deal
Preheader: Sale ends tonight at midnight. 40% off sitewide.
Keep it short. Most clients display 40–90 characters of preheader text depending on the device. Write the most important part first and treat anything after 50 characters as optional.
Don't repeat your subject word-for-word. If you're just going to say the same thing twice, leave the preheader empty — at least then the client will pull something real from your email.
How to implement a preheader in HTML
The standard implementation is hidden text near the top of the email body:
<span style="display:none;max-height:0;overflow:hidden;mso-hide:all;">
Your preheader text goes here. Keep it under 90 characters.
</span>
The display:none hides the text from visual rendering. max-height:0 and overflow:hidden are fallbacks for email clients that don't support display:none. mso-hide:all hides it from Outlook.
Place this immediately after the opening <body> tag, before any visual content.
Padding out the preheader
Some senders use "padding" after their preheader text to prevent the email client from pulling additional text from the body. The technique uses repeated whitespace or zero-width Unicode characters:
<span style="display:none;max-height:0;overflow:hidden;mso-hide:all;">
Your preheader text here.
‌ ‌ ‌ ‌ ‌
‌ ‌ ‌ ‌ ‌
</span>
‌ is a zero-width non-joiner — a Unicode character with no visible width that breaks up the whitespace sequence so clients don't collapse it. This forces the inbox preview to end after your preheader text rather than pulling words from your first heading.
This technique adds a few hundred bytes to your email and should be used selectively. For short emails it makes little difference. For long emails or newsletters where the next visible text would be odd inbox preview text, it's useful.
The Preheader Generator tool
The Preheader Generator in EmailingSimply lets you preview how your subject line + preheader will look across approximate representations of Gmail, Apple Mail, and mobile. Use it to check character counts and see the visible output before sending.
Common mistakes
Using the same preheader for every email. This reduces its value over time — frequent openers learn to ignore it.
Leaving it empty on transactional emails. Transactional emails (receipts, confirmations, shipping notices) often have strong natural preheader content already in the body. Let the email client pull it, or write something useful.
Making it longer than the visible limit. Write the most important information in the first 50 characters. The rest is bonus for clients that show more.
Conflict with the subject. "Subject: Your cart" + "Preheader: Your cart is waiting" is redundant. Use the second slot for new information.