Preheader text (also called preview text) is the short snippet that appears alongside or below the subject line in a recipient's inbox before they open the email. A compelling preheader can significantly improve open rates.
There are two distinct problems users encounter with preheader text, and they require different solutions:
- Problem A: The preheader field is not visible or available in the email builder.
- Problem B: The preheader text is set correctly but does not appear in recipients' inboxes.
Problem A: Preheader field not available in the builder
What's causing this
The dedicated Preheader field is only available in the Composer email builder. If you are using the legacy editor (also called the Classic Editor), this field does not exist. This is a feature difference between the two builders, not a bug.
Fix: Switch to Composer
- Open or create your email in Acoustic Campaign.
- If you are in the legacy editor, you will need to recreate or migrate the email in Composer. Note: Acoustic does not provide an automatic migration tool between builders.
- In Composer, open the Details pane (accessible from the sidebar or top settings panel).
- Enter your preview text in the Preheader Text field. Aim for 40–100 characters for optimal display across email clients.
For more information, see Create an email in Composer.
Workaround: Hidden HTML text (legacy editor only)
If switching to Composer is not immediately possible, you can simulate preheader behavior by placing hidden HTML text at the very top of the email body — specifically, your preheader text in a <span> element styled with display:none or a very small font size.
Important limitations of this workaround:
- Some email clients may display the hidden text briefly before the CSS takes effect.
- Spam filters may penalize emails that contain hidden text.
- Results are inconsistent across email clients and devices.
Note: The hidden-text workaround is not recommended for production emails. Migrating to Composer is the proper long-term solution.
Problem B: Preheader is set but not showing in inboxes
What's causing this
Even when preheader text is correctly configured in Acoustic Campaign, whether it appears in an inbox is entirely controlled by the recipient's email client (Gmail, Outlook, Apple Mail, Yahoo Mail, etc.). Acoustic transmits the preheader text in the email HTML — what happens to it after delivery is outside Acoustic's control.
Each email client has its own rules about:
- Whether to display preheader text at all
- How many characters to show
- Whether to pull text from the preheader field, the first line of the email body, or a combination of both
What Acoustic controls vs. what it doesn't
| Acoustic controls | Acoustic cannot control |
|---|---|
| Including preheader text in the email HTML | Whether the recipient's email client displays it |
| Encoding the text so it is accessible to email clients | How many characters the client shows |
| Ensuring correct HTML structure for the preheader | The position or style of the preview text in the inbox |
How to verify your preheader is working
- Use a rendering tool: Test with Litmus or Email on Acid to preview your email across 90+ email clients at once.
- Send test emails: Send to accounts on Gmail, Outlook, and Apple Mail to check rendering in the most widely used clients.
- Keep text between 40–100 characters: Some clients truncate at 40 characters; others show up to 100. Staying within this range gives you the best coverage.
- Never leave the preheader field empty: If blank, email clients will pull the first visible text from your email body as the preview — which may result in undesirable text such as "Click here to view in browser" or navigation link text.