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The Best Types of Subject Lines to Improve Open Rates

Hailee Franco Tactics

You spend hours writing amazing email content guaranteed to lead to sales or provide customers with valuable information. Then you send the email and notice your open rates are extremely low. This is probably because you spent so much time writing the content that you didn’t consider the email’s subject line.

This simple line of text is the first thing your customer sees, meaning it should be the most important copy you write. In fact, 33 percent of emails are opened based on the subject line alone. A great subject line can increase open rates, getting your content in front of more people. So what types of subject lines increase open rates?


Customers want to know what is in it for them when receiving an email. This means self-interest subject lines should be used frequently as they provide your customer with a benefit to open. They should give the recipient an idea of what to expect when they open the email, while also meeting a need or desire. These subject lines also give your business transparency by making it obvious what the purpose of the email is.

Examples of self-interest emails:

  • How to write the perfect subject line
  • 10 ways to improve your blog layout
  • Become a content marketing expert
  • 21 video mistakes businesses make and how to avoid them
  • Increase sales (Get the formula)


Humans are naturally curious, making headlines that peak a person’s curiosity extremely effective. These are the exact opposite of self-interest subject lines. They work by not giving too much information away which, when done right, gets recipients to open. Where self-interest subject lines should be used often, curiosity subjects should not. When used too much, your customer base can lose interest.

Examples of curiosity subject lines:

  • Oops, did we do that?
  • Email or direct mail?
  • Our favorite new product
  • Buy this, not that
  • I’m quitting cold turkey


Most of us love a good offer, so including a special offer in the subject line of an email can create higher open rates. Not only that, it can cause potential buyers to pull the trigger and purchase your product or service. However, not all special offers should be discounts. Yes, discounts can be used, but you can also include a bonus for buying a product, or a free download. Using action words like download or receive help show users how they can expect to obtain the bonus.

Examples of offer subject lines:

  • Download the Ultimate Content Marketing Strategy
  • Swipe this versatile email template [PDF]
  • Buy 2 years of service and receive a free Ebook
  • [TEMPLATE] The complete content calendar for digital marketers
  • Blog posts you will want to use. A downloadable guide

Crafting great subject lines can take time, but when done right help improve open rates. With 33 percent of emails being opened based completely on their subject lines, businesses must create the best one possible. Try the 3 subject line types outlined above and see how they improve your email engagement.