What is Preview Text? Preview text, sometimes known as the preheader, is the snippet of text that appears after the email subject line in most email programs. It is a feature that email marketers can use to improve their delivery rates, by improving how their message looks in the inbox. It's often overlooked in message creation. If you do not create it in your message, email clients will display the first part of your message in its place. To edit the subject line and preview text for a regular email campaign, follow these steps. Navigate to the Campaign page. Click the name of the draft campaign you want to work with. In the Subject section, click Edit Subject. Enter the Subject and Preview text you want to use.