Your email might be brilliant, but it doesn’t matter if nobody opens it. The subject line is the only part of your email that everyone sees, and it gets a fraction of a second in a crowded inbox, right between a delivery update and a message from someone’s mum.
Writing good ones isn’t about tricks. It’s about being clear, being useful and sounding like a human.
Key points
- A good subject line tells people what’s inside and why it’s worth their time.
- Keep it short enough to read on a phone screen without being cut off.
- Use the preview text, the line after the subject, as a second chance to win the open.
- Avoid tricks like fake “RE:” or false urgency. They might win one open and lose a subscriber.
What makes someone open an email?
When people scan their inbox, they’re asking two quick questions: who is this from, and is it worth my time right now? Your sender name answers the first one, so make sure it’s recognisable, like your business name or a real person’s name at your business.
The subject line answers the second. The ones that work usually do at least one of these things:
- Promise something useful: “Five ways to make your garden ready for winter”
- Spark curiosity, honestly: “The mistake we see on almost every quote”
- Speak to a specific person: “For café owners: a simple way to fill quiet Tuesdays”
- Feel timely: “Last day to book before the Christmas rush”
Keep it short, and front-load it
On a phone, long subject lines get cut off. Put the most important words first, so even a shortened line makes sense. “Your spring checklist is here” survives being trimmed. “We wanted to let you know that our spring checklist is now ready” doesn’t.
Don’t forget the preview text
Most email apps show a line of text under the subject. If you don’t set it, the app grabs the first words of your email, which is often “View this email in your browser”. That’s a wasted opportunity.
Treat the preview text as the second half of your subject line:
| Subject line | Preview text |
|---|---|
| The quote mistake we see every week | And the two-minute fix that makes yours stand out |
| Your autumn checklist is here | Six jobs to do before the first frost |
| A small change to our opening hours | From next month, we’re open later on Thursdays |
Sound like a person
The emails that get opened most often feel like they came from someone, not something. Write the subject line the way you’d write to a customer you know. Lowercase is fine. A question is fine. A little personality is very fine.
If it would look strange in a message from a friend, think twice before putting it in a subject line.
What to avoid
- ALL CAPS and lots of exclamation marks. They look like shouting, and spam filters notice them.
- Fake replies and forwards. Starting with “RE:” or “FWD:” when it isn’t one feels like a trick, because it is.
- False urgency. “Last chance!” every week trains people to ignore you.
- Vague lines. “Newsletter #14” or “October update” give nobody a reason to open.
- Promising what the email doesn’t deliver. You’ll get the open once. After that, people remember.
Test, but don’t obsess
Most email tools let you send two subject lines to a small part of your list and send the winner to everyone else. It’s a great way to learn what your readers respond to. Just remember that one test is a hint, not a law. Look for patterns over several sends.
If you’re building your list from scratch, our guide to what to send after someone joins covers the first few emails.
Questions people also ask
Should I use emojis in subject lines?
Sparingly, and only if they suit your brand. One relevant emoji can help a line stand out. Several can look like spam, and some may not display correctly on every device.
Should I put the person’s name in the subject line?
It can help, but it’s become common enough that it doesn’t guarantee anything. A subject line that’s genuinely relevant to them matters more than seeing their own name.
What’s a good open rate?
It varies a lot by industry and list, and privacy features in some email apps now make open rates less reliable than they used to be. Compare your results against your own past emails, and pay more attention to clicks and replies.