What is email preheader text?
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You're scrolling through your inbox, deciding what to open. Subject line catches your eye. Then you glance at that little snippet of text next to it. That snippet is the preheader.
Preheader text (also called preview text) is the short line of copy that appears right after the subject line in most inbox views. You didn't write it as body copy. It shows up before the reader has opened a single thing.
Here's where you'll see it in action: Gmail displays it in the inbox list view, right next to the subject line in a lighter grey font. Outlook shows it below the subject in the reading pane preview. Apple Mail on iOS shows a line or two beneath the subject in both inbox list and notification views. Most modern clients follow a similar pattern.
The typical visible length is somewhere between 40 and 130 characters, depending on the client, device, and screen size. Mobile tends to show less. Desktop often shows more. There's no single safe number, which is why the first 60 characters of your preheader carry the most weight.
If you don't set a preheader deliberately, clients will pull the first readable text from your email body. That might be a navigation link, a "view in browser" notice, or alt text from an image. Not ideal. Setting your preheader is always worth the two minutes it takes.
Think of the subject line and preheader as a team. The subject line gets attention. The preheader earns the click. A subject like "Your order is ready" pairs well with a preheader like "Pick it up before 6pm today" because it adds something new. A preheader that just repeats the subject line wastes the slot entirely.
And most ESPs have a dedicated preheader field in their editor. In Mailchimp, it sits right below the subject line in the campaign setup. Klaviyo, Brevo, and MailerLite all have the same pattern. If you're working in raw HTML, you add a hidden span near the top of the email body with a style of display:none and max-height:0.
Once you understand what preheader text is, the natural next question is how to write one that actually improves opens. That's covered in preheader optimization.
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