Preheader
Email MarketingAlso: Preview Text · Preheader Text · Snippet Text
Quick definition
A preheader is the short line of text that appears next to or beneath the subject line in an inbox preview, before the email is opened. If you don't set one deliberately, most inboxes pull the first line of body copy instead, which is often unhelpful or repetitive.
How it varies across Australia
Open rate lift from a written preheader varies by list and industry, but Australian senders who leave it to default text consistently underperform against senders who treat it as a second headline. The gap shows up most on mobile, where inbox previews are shorter and every word matters more.
See email marketing benchmarks across Australian industries →What it actually means
Picture the subject line as the headline of a newspaper story and the preheader as the subhead underneath it. Readers scan both before deciding whether to open the page. Most email marketers write a careful subject line, then let the inbox pick up whatever text happens to sit first in the email body, which is often 'View this email in your browser' or a stray logo alt text.
The preheader is controlled with a small snippet of hidden HTML, usually white text on a white background sitting right after the opening body tag. Gmail, Apple Mail and Outlook all read it and display it next to the subject line in the inbox list. It does not appear once the email is opened.
The two working together matter more than either alone. A subject line creates curiosity or urgency. A good preheader either resolves that curiosity a little further or adds a second reason to open, without giving away the whole story. Segmentation plays a role here too. A preheader that works for a cold list rarely works for a warm one, because the context the reader brings is different.
The subject line gets the credit. The preheader does half the work and gets none of the attention.
How it shows up
Preheader quality shows up first in open rate, particularly on repeat sends to the same segment where subject lines alone start to lose novelty. It also shows up in inbox screenshots during a subject line audit, when a marketer finally sees what recipients have been seeing for months. On mobile it's more visible still, because Apple Mail and Gmail apps show less text per line, so a weak or truncated preheader gets cut off mid-sentence and reads as broken rather than intriguing.
Where people get this wrong
Related terms
Common questions
How long should a preheader be?
Keep the core message inside the first 40 to 50 characters. Mobile inboxes truncate earlier than desktop, so anything past that point is a bonus for desktop readers but invisible to most mobile ones.
What happens if I don't set a preheader?
The inbox pulls the first visible text or alt text from the email body instead. That's usually unsubscribe language, a logo description or navigation text, none of which helps the reader decide to open.
Should the preheader repeat the subject line?
No. Treat it as a second line of copy that adds new information or resolves curiosity slightly further. Repeating the subject line wastes the space and gives the reader nothing extra to act on.
Does the preheader affect deliverability?
Not directly. It has no bearing on spam filtering or inbox placement. Its job is purely to influence whether someone opens the email once it's already sitting in their inbox.
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About New Rebellion
New Rebellion is a marketing intelligence consultancy. We build tools, score Australian businesses on how their marketing actually performs, and publish Debrief every day. This dictionary is part of how we work in the open.
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