Subject Line
Email MarketingAlso: Email Subject · Email Headline
Quick definition
The subject line is the first line of text recipients see in their inbox. It determines whether the email gets opened. Everything else in the email is irrelevant if the subject line fails.
Where it shows up in the data
What it actually means
The subject line sits at the very top of the email marketing funnel. If it doesn't earn the open, nothing that comes after it matters — not the offer, the design or the copy. A good subject line creates curiosity or communicates clear value without overpromising. It should be specific enough to set accurate expectations and intriguing enough to create a reason to click. On mobile, only 30 to 40 characters are visible before truncation, which means front-loading the key information is critical.
The best subject lines make you feel like you'd be missing something if you didn't open. The worst make it obvious you're about to be sold to.
The Australian context
Australian email audiences have among the world's highest digital literacy and are quick to unsubscribe from lists that feel like broadcast advertising. Conversational subject lines that match the tone of a direct message ('Quick question for you') tend to outperform corporate-sounding alternatives in Australian B2B and professional services contexts.
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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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