Your subject line and your from name are most of what someone sees before deciding whether to open. Get the subject line right and the rest of the email gets a chance. Get it wrong and nothing else matters, because nobody sees it.

The good news is that writing better subject lines is a learnable skill, not a talent. Here’s what tends to work, what to avoid, and how to find out what works for your own readers.

What makes people open

A few things drive most opens:

  • Relevance. The subject tells the reader this is about something they care about.
  • Curiosity. It gives them a reason to want the rest, without tricking them.
  • Recognition. They know who it’s from and trust it’ll be worth their time.
  • Timeliness. Real deadlines or news make “now” feel worth it.

Notice that recognition isn’t really about the subject line at all. A newsletter people trust gets opened with fairly plain subject lines, which is why consistency matters as much as cleverness.

What a good subject line has

Clarity

Say what’s inside. Readers skim their inboxes and decide in a second or two, so a clear subject usually beats a clever one. For newsletters, leading with the most interesting story in the issue is a reliable pattern.

The important words first

Phones show much less of a subject line than desktops do, and how much shows depends on the app and the screen. Rather than chasing an “ideal” character count, put the words that matter at the start. If the beginning makes sense on its own, it doesn’t matter where it gets cut off.

Relevance and personalization

Personalization can help, but it’s about relevance more than names. “New: the deliverability checklist you asked for” is personal in a way that “Hi Sarah” isn’t. If you do use names, set a fallback so nobody gets “Hi ,”.

Honest curiosity

Questions and intriguing statements work, as long as the email delivers on them. If the subject promises something the email doesn’t have, people notice, and they open you less next time.

Emojis, sparingly

An emoji can help a subject line stand out, if it suits your brand. One is plenty. Test it rather than assuming.

Common mistakes

  1. Overpromising. Subject lines that oversell lead to disappointment, unsubscribes and complaints. Misleading subject lines are also against the US CAN-SPAM Act.
  2. Shouting. All caps and piles of exclamation marks look like spam to readers, even if they don’t to filters.
  3. Worrying too much about “spam words”. You’ll find long lists of words like “free” that supposedly send email to spam. It’s mostly a myth now. Modern filters care far more about your sender reputation and how readers react than about individual words. Write normally.

Mobile

  • Front-load the important words
  • Keep it focused on one idea
  • Use your preview text as a second line that adds to the subject rather than repeating it
  • Check how it looks on a real phone before sending

Testing subject lines

A/B testing is the best way to learn what works for your list: send two subject lines to small samples, then send the better one to everyone else.

One important change: judge subject line tests on clicks, not opens. Since Apple Mail Privacy Protection arrived in 2021, Apple Mail records opens automatically for many users, so open rates can pick the wrong winner. Clicks tell you which subject line brought in people who actually read.

Keep a note of what wins over time. Patterns across a few months of tests are far more useful than any single result.

Examples to adapt

  • Relevance: “Your weekly deliverability roundup: Gmail’s new rules”
  • Curiosity: “The one setting most newsletters get wrong”
  • Urgency: “Last day: 50% off annual plans”
  • Social proof: “What 10,000 readers asked us this month”
  • Exclusivity: “Early access for subscribers only”
  • How-to: “How to fix a falling open rate”

Adapt them to your niche with the language your readers use, and only use urgency or numbers when they’re true.

Final thoughts

Good subject lines come from knowing your readers and being honest about what’s inside. Write clearly, put the important words first, test on clicks, and keep a record of what works.

If you’re stuck, keep a folder of subject lines you couldn’t help opening and work out why they worked. AI tools like ChatGPT are also handy for generating variations of a subject line you’ve already written, to give you more options to test.

References

  1. [1] ChatGPT — chatgpt.com