How to write subject lines that get opened

Most people decide whether to open an email in about a second. In that second they see three things: who it is from, the subject line and the preview text. You cannot change much about the first, so the other two do most of the work.

Rule 1: Say what is inside

Clear beats clever. If someone cannot tell what your email is about, they skip it. Compare these:

• Weak: "Big news!"
• Better: "Our new delivery area now includes Lekki and Ajah"

The second one tells you exactly what you will learn and who it is for.

Rule 2: Keep it short

Many people read email on their phone, where long subject lines get cut off. Aim for around six to ten words. Put the most important words first, so the meaning survives even if the end is cut.

Rule 3: Make it about the reader

Your reader cares about their problem, not your announcement. Turn your news into a benefit for them.

• Business first: "We launched a new invoicing feature"
• Reader first: "Get paid faster with one click invoices"

Rule 4: Use numbers and specifics

Numbers stand out in a busy inbox and set clear expectations.

• "5 mistakes that send your emails to spam"
• "Your order ships in 2 days"
• "3 recipes for a busy weeknight"

Rule 5: Write good preview text

Preview text is the short line that appears next to or under the subject. If you leave it empty, your email app shows the first words of your email, which is often "View this email in your browser". That wastes valuable space.

Use the preview text to add a second reason to open:

• Subject: "Your guide to SPF, DKIM and DMARC"
• Preview: "Set it up in under an hour, no tech skills needed"

Rule 6: Sound like a person

Emails from people feel more personal than emails from brands. Try writing your subject line like you would text a customer. Lowercase, casual subject lines can work well for newsletters. Formal ones work better for invoices and account updates. Match the tone to the email.

What to avoid

• ALL CAPS and lots of exclamation marks. They look like shouting and can trigger spam filters.
• Tricks, like starting with "Re:" when it is not a reply. People feel fooled and unsubscribe.
• Promises the email does not keep. If your subject says "free", the email must deliver something free.
• Emoji overload. One emoji can help. Five looks messy.

Test and learn

Most email tools let you test two subject lines with a small part of your list, then send the winner to everyone else. This is called an A/B test. Test one thing at a time, like a question against a statement, so you know what made the difference.

Keep a simple note of what works with your audience. After a few months, you will have your own rule book that beats any general advice, including this article.

Ten examples to adapt

• "Your free checklist is ready"
• "Quick question about your last order"
• "We fixed the thing you asked for"
• "3 ways to cut your delivery costs this month"
• "Last day for free shipping"
• "New in: the shoes you saved"
• "How Bisi grew her bakery list to 2,000"
• "Is this still the right email for you?"
• "Your weekly tip: follow up within an hour"
• "Doors close Friday for the workshop"