A preheader is also called preview text. Email platforms can let you set it separately from the subject line. Without a chosen preview, an email client may take text from the start of the message. The amount displayed varies, so there is no single visible length to assume. Source: Mailchimp: Email design guide Source: Mailchimp: About preview text

Give the subject a useful companion

Use the preheader to add a relevant detail, such as the departure period or the focus of a holiday guide. Keep the wording accurate and useful on its own. This gives the reader more context before opening the message without simply repeating the subject.

Read a real inbox preview

Send a test to the inboxes your team uses and inspect the subject and preview together. Check that cut-off text does not hide an important qualification or expose a stray instruction. A real preview makes those problems easier to see than the email editor alone.

Written and updated by Travelgenix. Sources checked on 19 October 2026. Practical advice and examples are Travelgenix editorial guidance.