Email Preheader Text: Write the Line After the Subject

In most inboxes, an email shows three things before it is opened: the sender, the subject line and a short line of preview text. That last line is the preheader. Many marketers ignore it and let the inbox pull in whatever appears first in the email, such as "View this email in your browser". A well-written email preheader text turns that spare line into a second chance to persuade someone to open.

What preheader text is

The preheader, also called preview text, is the snippet displayed next to or below the subject line in an inbox list. It comes from the first text in the email's code, unless you set it deliberately. Mail apps differ in how many characters they show, and some show none, but on many phones and desktop clients it is visible.

Because it appears alongside the subject line, the two should work together as a pair. The subject sets the topic; the preheader adds detail, context or a reason to open. For tips on the subject itself, see email subject lines that get opens.

Why it matters

1. It fills valuable space. On a crowded inbox, the preview takes up part of your visible message.
2. It avoids wasted text. Without a deliberate preheader, clients display navigation text, links or alt text, which look sloppy.
3. It can raise opens. A clear preview can answer "is this relevant to me?" at a glance.
4. It supports accessibility. Screen readers read the preheader, so it should make sense and not be filler.

Opens are less reliable now because some mail apps load images automatically. You can still judge effects through clicks and conversions. See email marketing metrics explained.

How long should it be?

Display length varies widely. Some clients show around 40 characters on a phone and over 100 on a desktop. A practical approach is to write a preheader of roughly 40 to 90 characters and put the most important words first, so the message still works if it is cut off. Check how it appears in the clients your audience uses, and use the data in your email platform to see which are most common.

Ways to use the preheader

Extend the subject line

If the subject makes a statement, the preheader can complete the thought.

• Subject: "Three checks before you launch your site"
• Preheader: "A short checklist to catch the most common mistakes"

Add a benefit or detail

• Subject: "Our spring workshop is open for booking"
• Preheader: "Two sessions, small groups and a free template pack"

Create curiosity responsibly

• Subject: "The email mistake we all make"
• Preheader: "It takes two minutes to fix, and it improves replies"

Avoid misleading teasers. The email must deliver what the preview promises.

Provide logistics

For event or transactional emails, a preheader may state the date, deadline or action: "Your appointment is on Friday at 10 am. Tap to confirm."

What to avoid

• Repeating the subject line. It wastes space. Add new information.
• Generic phrases such as "View in browser" or "Having trouble reading this email?"
• Pushing important content out of view. Put the key point first.
• Overpromising or using clickbait that damages trust.
• Spammy language in capital letters or excessive punctuation. This can also trigger spam filters; see the email deliverability checklist.
• Hidden clutter. Do not stuff the preheader with long strings of invisible characters unless you understand the effect; some approaches can look odd in certain clients.

Set the preheader in your tools

Most email platforms have a dedicated field for preview text, usually next to the subject line. Fill it in for every campaign. If your platform lacks this field or you are writing HTML emails by hand, you can add a hidden block of text at the very top of the email body, styled so that it is not visible when the email is opened but is picked up by inbox previews. Follow your platform's guidance, and test the result.

For automations, set preheaders for each email in the sequence, such as those in your welcome series. Do not leave them blank.

Write with the reader in mind

Ask: if this were the only text I saw, would I know why to open? Use plain, specific language. If you segment your list, adjust the preview for each group, as described in email segmentation by behavior. Consider tone, too. A friendly note works for a newsletter; a crisp, factual line works for a transactional message.

Personalisation can help when it adds meaning, such as mentioning a topic they read about earlier. Using a first name alone may not improve results. Make sure personalisation fields have fallbacks, so that an empty field does not produce awkward text.

Test and learn

Treat preheaders like subject lines: test them. Use an A/B test where only the preheader changes, measuring clicks and conversions rather than opens alone. Try variations such as a benefit versus a curiosity line, a short phrase versus a longer sentence, or a question versus a statement. Keep a log of what works for your audience. The email A/B testing guide outlines how to run clean tests.

Before sending, preview the email in several inboxes, on both mobile and desktop. Many platforms offer a preview tool. At minimum, send a test to your own accounts on different providers.

Preheader examples by email type

Newsletter: Subject: "Five checks before you hire a web designer". Preheader: "A short list that can save weeks of rework".

Promotion: Subject: "Our spring offer ends Friday". Preheader: "Free setup for new clients until midnight, details inside".

Event invitation: Subject: "Join our free SEO workshop". Preheader: "Thursday 5 pm IST, live Q and A, recording for all registrants".

Abandoned cart: Subject: "Still thinking it over?" Preheader: "Your basket is saved, and we are here if you have questions".

Welcome email: Subject: "Welcome, your checklist is inside". Preheader: "Start with step one today, it takes ten minutes".

Transactional: Subject: "Your invoice for March". Preheader: "Amount due, payment options and the due date".

Each example adds something the subject line does not say and ends with a clear, honest promise.

Preheader and accessibility

Screen reader users hear the preview text, so write it as a complete, meaningful phrase. Avoid decorative symbols or strings of emojis that are read aloud awkwardly. If you use emojis, use them sparingly and test how they read. Make sure the preheader text is not hidden in a way that causes it to be read twice in the opened email. Combine it with a logical heading structure and alt text in the body to make the whole message usable by everyone.

Common platform quirks

Different platforms handle preheaders differently. Some automatically add extra text after your preheader to fill the preview, such as a link to view the email in a browser. Others let you control this. Check your tool's documentation, and send tests to a handful of providers. If you notice odd text appearing after your preheader, adjust the template or add padding text according to your platform's advice. Keep a note of the findings so that you and your colleagues apply the same approach across campaigns.

Make it a habit

Add a preheader step to your email checklist so it is never skipped. Before each send, read the subject and preview together and ask whether they make a clear, honest, appealing pair. Keep a small swipe file of preheaders that performed well and the ones that fell flat, along with the subject lines they were paired with. After a few months you will have an internal guide that reflects your own audience instead of generic advice, and new team members can learn your style quickly by reading it.

Checklist

1. Write a preheader for every email.
2. Keep key words in the first 40 characters.
3. Add information the subject does not already give.
4. Make sure it is accurate and honest.
5. Preview it in at least two clients.
6. Review results and adjust.

Small details like this accumulate. If you would like help improving your email campaigns, contact me.