Here’s the thing: You want to write email subject lines that actually work. You know…

  • …the subject lines that get noticed in busy inboxes [because you compete against the 121 emails an average office worker receives every. single. day.]…
  • …the subject lines your subscribers actually open
  • …because you know the only way to get traffic + conversions—and ultimately sales—is to stand out.

In short: You need to know what makes a great subject line work to be successful as an email marketer.

The 7 email subject line tips in this article are backed by 20 studies and CoSchedule’s very own data from our Campaign Monitor account.

The goal here is to help you learn and remember the mechanics the best-performing email subject lines often share.

But before we get into that, let’s give you a great starting point.

Start with these 20 creative email subject line example templates

Sometimes, that blinking cursor is the most intimidating thing in the world.

So use the following email subject line templates as a type of “swipe file”. Copy, paste, then fill in the blanks to get started.

  1. Stop {Undesirable Emotion} Now
  2. {Desirable Outcome} (Your First 3 Steps)
  3. New {Thing}: What It Means For {Audience’s Role}
  4. What {Credible Influencers} Are Saying About {Topic}
  5. {Someone Audience Looks Up To} Can Afford Any {Product}, She Uses…
  6. Best {Emoji} + {Emoji} + {Emoji} = {Emoji}
  7. {Topic}, {Topic}, and {Seemingly Unrelated Topic}?
  8. {Personalized Company Name} + 497% More {Need} = {Emoji}
  9. {Emoji} Your {Emoji} With…
  10. {Personalized Name}, Earn {Something Desirable} Today Only
  11. You’re Missing Out On {Something Desirable}
  12. Tonight Only: A {Audience’s Role}’s Dream
  13. Want 587% More {Something Desirable}? {Emoji}
  14. This Is A Sales Email {Emoji}
  15. Don’t Forget! {Event} Today {Emoji}
  16. …When You’re Sick And Tired Of {Something Undesirable} {Emoji}
  17. “{Quote}”
  18. A {Topic} Process To Reduce 30-50% Workload {Emoji}
  19. {Topic} + {Topic} + {Topic}
  20. “I Love {Something Undesirable}!” (said no one ever)

Then, use the following 7 tips to optimize your subject line.

1. Leverage words that have been proven to boost email open rates

My research into email subject line mechanics dug up 100 words, terms, and symbols that are highly like to influence open rates when you use them in your subject lines:

CoSchedule – Email Subject Lines - Words to Increase Open Rates

Further analysis suggests you’ll get the best open rates by using 3 or more of the words/terms and/or symbols from that list in your subject line.

2. Remove words that reduce open rates (or trigger spam filters)

Just as there are words that typically increase email open rates when you use them in subject lines, there are words that negate those opens, too.

Here’s a shortlist of 100 words, terms, and symbols to avoid using in your email subject lines:

CoSchedule – Email Subject Lines - Words to Decrease Open Rates

It’s best practice to use zero of these words, terms, or symbols in your subject lines.

3. Include a number in your subject line

Including numbers in blog post headlines increases clickthrough rates by 206%.

Sure, that’s blog post titles.


…titles and subject lines serve a very similar purpose: Increase clicks from a list (blog post category pages, social news feeds, email inboxes, etc.).

It turns out, like blog post headlines, using numbers in your subject lines increases email open rates.

A recent study from YesWare that analyzed 115 million emails (!!!) suggests email open and reply rates are higher when a number is present in the subject line.

 CoSchedule – Email Subject Lines with Numbers

HubSpot’s anecdotal research backs up YesWare’s findings, suggesting:

[…] using data and numbers is a great way to get your emails noticed, demonstrate a clear and straightforward message about your offer, and set the right expectations.

Just like with blog titles, using numbers in your subject line is an effective email marketing best practice. You might use numbers to refer to the title of your listicle, the page length of the offer you’re sending, a specific discount, or the numerical benefit of a particular resource you’re providing — like “Join more than 750 others at this event!

Include at least one number in your subject line to boost your email open rates.

4. Put an emoji in your subject line 😊

Campaign Monitor recently researched the use of emojis in subject lines to understand if their inclusion increased open rates. When I chatted with Kim Courvoisier a few months ago, who was a marketer here at Campaign Monitor, she suggested:

Brands that are using emojis have seen a 56% increase in their unique open rates. This isn’t a report from experience. We’re really seeing an increase in emojis, and you can use them as a brand appropriately, and they do add a nice little bit of flare and attention-getting in the inbox.

If you’re wondering where you can find emojis:

  • Windows: PCWorld suggests using the WIN + . (actual period punctuation mark) to open the emoji keyboard.
  • Mac: Hit Control + Command + Spacebar to open the emoji window.
  • If neither of these suggestions works: Check out GetEmoji and copy/paste.

Best practice suggests using 1-4 emojis in your subject line will boost your email open rates.

5. Write the best length email subject line: 17-24 characters…

While the 20 studies analyzed for this article differed drastically on the topic of email subject line length, there is some general best practice advice throughout:

Keep your subject lines short.

So… why is this good advice?

50% of all emails are opened on mobile devices. iPhones show about 35-38 characters in portrait mode, and Galaxy phones show roughly 33 characters in portrait mode.

Long story short: Make sure the 50% of your subscribers who will open your email on their mobile device can actually read the entire subject line.

CoSchedule – Boost Email Open Rates with Character Length

Best practice suggests subject lines that are 17-24 characters long are most likely to boost your email open rates.

6. …And make your subject line 3-5 words long

The studies suggest the more words you use in your subject line, the fewer opens you’ll get.

Best practice = short number of characters + short number of words

CoSchedule – Boost Email Open Rates with Number of Words

So use 3-5 words in your subject line to boost your email open rates.

7. Test title case subject lines

YesWare’s research into 115 million emails suggests that subject lines in title case are most effective at boosting your open and reply rates.

CoSchedule – Email Subject Lines – Title Case

That study suggests the psychological reasoning behind title case’s success is perceived authority:

Even something as small as using title case instead of sentence or lowercase in an email subject line is an authority badge for the sender.

It’s like showing up to an interview in a suit instead of a pair of shorts.

For the curious…

  • Title case: Pack My Box With Five Dozen Liquor Jugs
  • Sentence case: Pack my box with five dozen liquor jugs
  • Lower case: pack my box with five dozen liquor jugs

Write your subject lines in title case to boost your email open rates.

Wrap up

You want sales.

Without email opens…

…you get zero clicks to your website…

…which means zero traffic that you can convert…

…which means zero sales.

Something as simple as email open rate can help you concentrate on the lead indicators that influence more significant metrics down the funnel.

So, if you’re thinking of improving your open rates with a little help from data:

  1. Use a few of the words that are proven to increase open rates.
  2. Avoid the terms that typically decrease open rates.
  3. Test using a number in your subject line.
  4. Include at least one emoji.
  5. Make it about 17-24 characters long.
  6. Shoot for approximately 3-5 words.
  7. Write it in title case.

You’ve got this.