Email Preheader Text: What It Is and How to Use It

The preheader (also called preview text) is the short line of text an inbox shows next to or beneath the subject line before the email is opened. It is prime real estate that many senders waste, and getting it right can lift your open rate.

Think of it as a second subject line

Readers use the subject and preheader together to decide whether to open. If you leave it empty, the inbox pulls the first text it finds in your email, often a link, an address, or boilerplate, which looks careless. Writing it deliberately gives you a second chance to make the case.

How long should it be?

Visible length varies by client and device, but roughly the first 40 to 90 characters matter most. Put the important words first so the message survives truncation on mobile, where space is tightest.

Best practices

• Complement the subject line, do not repeat it.
• Front-load the value or the hook.
• Keep it specific and honest; avoid clickbait.
• Add a light call to action where it fits.

Stop the body text from spilling in

If your preheader is shorter than the space the inbox shows, it will pull in whatever comes next from your email body. The fix is a hidden preheader block followed by filler characters that absorb the remaining space, so only your chosen text appears in the preview. A good email tool handles this for you.

HTML Email Builder has a dedicated preview text field and inserts the hidden preheader and filler automatically, so the inbox shows exactly what you wrote and nothing leaks in behind it.