Best Practices for the Perfect Subject Line

You’ve spent a lot of time and energy crafting your email. It’s strong. It’s personal. It resonates for your reader. But your subject line is the email’s gatekeeper, and if it doesn’t pull your reader in, nothing in your email matters. It will be left behind a closed door. Or worse, your reader will simply delete it. 

So your subject line is a big deal. How do you write it so your email has the best chance of  being opened? We’ve compiled some key components to consider. You don’t need to use all of them—you’d have a long subject list instead of a single subject line! Instead, choose a few that make sense to you, maybe even A/B test them before you settle on the one you like. (10-20% of your audience is the rule of thumb for testing.)

Go for grabbing attention

You want your email to stand out in a sea of emails. Over 300 billion are sent every day around the world. Personalize your subject line. Use your reader’s name. Add one emoji. Be clever with your word choice and tone. Use humor. The best performing subject line words are introducing, discover, and recent. 

On the flip side, don’t go for ALL CAPS. (Did you know caps often trigger SPAM ALERT! in reader’s minds?) Other things that alert the SPAM filter include:

  • Emails without an unsubscribe button
  • Phrases like “act now” or “as seen on”
  • Links to unknown or questionable websites
  • Colorful and different sized fonts
  • Go easy on the exclamation marks!!!!!!!! 

Why is this important to me?

You need to know your reader. Show them the relevance of your product to them. How will it improve their life? In their world, what value does it have? You also need to be honest. The more your reader trusts you, the more they’ll invest.

Revisit your high school English class

Remember learning what makes a sentence stand out? Try using rhyme, alliteration, or onomatopoeia in your subject line. Leave out descriptive, filler words like really and amazing and astounding. Those words instill distrust. 

Create curiosity (In other words, leave your reader wanting more)

Use open-ended questions that beg for a click-through for answers. Make big promises you can fulfill—but only if your reader opens the email. And remember, being mysterious or misleading is not the same as being compelling.

Also create a clear call to action

Your reader wants to know what they will be asked to do if they open your email. Give them a good reason to do it. Positive action verbs are helpful here. Think join and discover and save. A sense of urgency can be effective too. If you reader knows they’ve got to adhere to a deadline, they’re more likely to act now.

Brevity is beautiful

Just about half of all emails are opened on a phone. So make your subject lines short and sweet. The worst thing is if your subject line is so long it gets cut off. Aim for forty characters, which is somewhere between five and seven words.

Finally, try writing your subject line last. You’re probably tempted to write it first, which makes sense, because it leads into the email. But if you wait to write it until your email is done, you’ll be much more confident in exactly the message you’re trying to convey.