Increase Your Email Open Rates With These 9 Subject Line Formulas

On average, people receive more than 120 emails per day. With all that email action in your customers' inboxes, it is essential to find ways to up your open rate.

Factors like time of day, type of browser or device, sender reputation, iOS15, and customer preferences all influence open rate. While you can't control all these factors, there is one thing you can do to dramatically improve your odds of success: write an irresistible subject line. 

Subject line strategy is a vital part of any email that you send, as it sets the stage for an open and click-through to your store or a completely ignored email. 

In this post, we’ll reveal nine proven formulas for creating subject lines that stand out from the crowd.

How Long Should Your Subject Line Be? 

Subject lines that are too short often fail because the benefit of reading isn’t clear. On the other hand, adding too much detail can also have a negative impact. More people use smartphones and smartwatches to browse, and screen width is limited – so long subject lines can be less effective.

What’s the perfect length? Opinions vary, but most studies agree that 40–50 characters or 9–14 words is optimal. It’s okay to bend the rules sometimes. Just keep in mind that relatively short subject lines are statistically most effective, but experiment and measure to discover what works best for your audience.

The “Hello” Subject Line

When someone signs up for your list or makes a purchase from you, it’s best practice to trigger a welcome campaign. This is your opportunity to greet new customers by telling them who you are, what you do, and why you do it. 

These subject lines are warm and fun, introducing customers to your brand. 


  • Oh, hey [first_name]! Welcome to the party. 

  • Welcome to the club. Here’s your [offer if you provide one]. 

  • Welcome to the [brand name] family. 

The Social Proof Strategy Subject Line

Buyers are influenced by other buyers. Create the temptation to follow the crowd by showing reviews from customers who love your products. 

For more information on why social proof is so effective and how to utilize it effectively, check out this fantastic Neil Patel article


  • 5 reasons to love us. 

  • 10/10 - The [product name] reviews are in. 

  • Meet our most popular [product]! πŸ‘€  

The Abandoned Cart Subject Line

Fact: Abandoned cart emails get higher engagement rates than any other type of email you send. Nail your email subject lines and watch your open rates increase.


  • Oops, you left something behind... 

  • Your [item names] are waiting for you. 

  • Did you forget something? 

The Personal Subject Line

Including someone’s name builds rapport and encourages engagement. Whatever the occasion, using someone’s name is sure to get their attention. 


  • [First name], meet our best sellers. 

  • πŸ‘‹  REVEALED: [First name]’s Free Gift.  

  • [First_name], don’t miss your 10% off discount!

The Product Launch Subject Line 

When it comes to launching products, people want the latest, freshest thing; nobody wants to be left behind. Including the idea that your launch is exclusive will make it more likely to be read.

People enjoy invitations. Inviting someone to “be the first to” do something, or find the answer to a perplexing question, is another angle on the same theme.


  • Guess what you’re getting early access to… 

  • Invite only: Get a first look at [your brand’s] new product. 

  • [Product name] is coming and you could get early access 🚨

The How-To Subject Line

Why does the ‘How-To’ subject line work? Because the value of your email is immediately apparent. The reader knows that opening your message will educate him or her on how to solve one of their problems.

When delivering a ‘How To’ subject line, focus on the benefits they will enjoy – making it enticing by offering something of value.


  • How to make [something that involves your product].

  • How to wow your mom this Mother’s day.

  • How to [accomplish something great using your product]. 

The Shocking or Unusual Subject Line

We all enjoy pleasant surprises, so an email that makes you chuckle and piques your curiosity is bound to encourage you to open the message.

These subject lines are curiosity-driven and compel people to stop, wonder what you could be talking about, and open your email to find out.

There isn’t a formula for shocking/unusual subject lines, so here a few that stood out in my inbox lately:

  • Oh πŸ’©! Last Chance for a FREE Gift! (BarkBox)

  • Don’t drink the Soap. It doesn’t taste as good as it smells. (Black Wolf) 

  • Disappearing soon… they’re here for a good time, not a long time, you know? (Doe Lashes) 

The Promotional Subject Line

Sending promotional emails is a given when you run an ecommerce shop. Make your promotional subject lines fun, on-brand, and don’t be afraid to throw in an emoji to grab people’s attention. 


  • πŸ”₯NEW [PRODUCT] | Tons of new styles!

  • The Easter 🐰  bunny brought you [product name] or [discount]

  • Meet our best sellers. (going fast)

The FOMO-Inducing Subject Line

Whether it’s a sale, product launch, or special occasion—FOMO, or fear of missing out, is real. Use urgent language to instill a sense of FOMO and get people to act quickly (without being spammy).


  • πŸ’¨ Ends tonight: [discount or sale]! 

  • This [product name] won’t be here for long!

  • Yikes, you ALMOST missed [discount]