Thought Leadership

5 Strategies to Improve Subject Lines and Increase Email Open Rates

Subject line tips that may help you increase open rates

How many subject lines come across your inbox every day? Which ones intrigue you the most? As a marketer your subject line is one of the most important components of your entire email. It is the first thing your recipients see in their inbox and will likely determine if they engage.

Below are some subject line tips that may help you increase open rates and lead your customers down a path of engagement.

1.  Track the Best-Performing Subject Lines

What resonates with your customers? Do your subject lines promote urgency with wording like "Last Chance" or "Exclusive Offer, Today Only"?  Do discounts that represent ‘dollars off’ produce higher open rates than those advertising ‘percent off’?  For example: “Save $25 now!” Vs. “Save 30% before it's over!”  Do your subject lines entice the reader to open for more information?

Action Steps: Answer these questions by going back and looking at open rates and subject lines from the past quarter; this will help you find the themes that produced the highest open rates. Next, go back further and review your data from the entire last year in order to get a comprehensive view of what your subscribers respond to and see if certain types of subject lines produce higher engagement and at what rate.  

2.  Consider How Your Subject Lines Look on Mobile

Yesmail's Q4 2015 Email Marketing Compass reported that over the past three years, more than half of all email opens have happened on mobile devices. The optimal lengths for email subject lines have been debated for years. However, it is important to keep in mind that mobile devices will show only 25-33 characters from a subject line.

Here is an example of a subject line that is 75 characters long and how it renders in a mobile device. You’ll notice that while the full subject line conveys a lot of information in a desktop environment, its mobile equivalent is a lot less informative. If you were to view this email on your mobile device, you’d know this is a promotion of a SALE but you would not realize this was a 4-hour, today-only sale.  

Full Subject Line:
SILVER EAGLE FLASH SALE: Your early access for today's 4-hour sale is here!

Silver Eagle Flash Sale

Here is a second example of a Subject Line that is just 22 characters; despite its conciseness, it encourages engagement through the use of a mystery offer and an emoji.  Who doesn’t love deals?

Old Navy Mystery Offer

Action Steps: Segment your audience based on platform/device use and test different subject lines. Don't let character length be a limiting factor. Test variations of shorter and longer subject lines in each platform to identify the length that prompts optimal engagement.

3.  Determine if Your Audience  Emojis

The use of these fun and expressive icons can help you stand out in the inbox. Using emojis within your subject line isn't a new idea, especially since they allow you to convey a lot of information in a single character. If your brand has a tone that supports emojis, using them could help encourage engagement and email opens.  

Action Steps:  Go to a source like or Try testing subject lines that utilize emojis but be aware that not all email clients and ISPs render emojis the same way. Make sure to use a rendering tool, such as Deliverability Intelligence, to confirm the emojis are rendering correctly in every email client because if a character isn't supported it could have a negative effect on your customers’ experience.

4.  Test Subject Lines on Non-Openers

If you have a compelling offer for your customers, an initial send to non-openers with a few subject line variations will help you identify the best-performing subject line to send to your engaged audience and help optimize engagement. Revise your subject line slightly with a few different approaches.  You can use keywords such as "Reminder" or others that communicate urgency, such as “Final Hours” or "Last Chance", or you can experiment with subject line personalization.

Action Steps: Pick a compelling offer and start with sending a few subject line variations for it to non-openers and non-purchasers. Review the open rates, click-to-open rates, conversion/revenue, and unsubscribe rates to identify the subject line winner from a holistic perspective. Deploy the winner to your engaged segment to ensure optimal message performance.

5.  Consider Developing Fun and Seasonal Emails

If you look at your calendar you can easily find a reason to celebrate each month. New Years, Valentine's Day, St. Patrick's Day, March Madness, Easter, Voting Day, National Leave The Office Early Day (June 2nd in case you’re wondering)… the opportunities are endless. 

For example: We just left another Tax Day behind. Shutterfly used this opportunity to provide some humor with a punchy subject line and fun creative that includes a happy dance.

Subject Line: Tax relief! FREE gift for you.


Other fun example of the day included Brugger’s Bales offering a baker’s dozen and two tubs of cream cheese for $10.40 (1040 is the name of one of the most recognized tax forms.)

Action Steps: Challenge yourself to use the right side of the brain and come up with some fresh and out-of-the-box ideas for your subject lines using seasonal events and holidays. Of course, some would speak more to your audience than others, so identify those early on so you’re ready to pounce on the engagement opportunity.  

Bottom line is that subject lines need to be strong if they are going to encourage engagement. Make sure to always communicate valuable information up-front; it will be a determining factor for opens. Of course, subject lines are not the only thing that impacts open rates. Other factors such as list hygiene, frequency, and segmentation are other areas that contribute to good email engagement, but those are topics for another day.     

Author Bio

Sherry Tippery

Sherry joined the Yes Marketing family in June 2003. Throughout the years Sherry has taken advantage of different opportunities representing the Client Services Organization at Yes Marketing. Starting as an Account Manager, Senior Account Manager and then Account Director building a cohesive team in the Omaha office. She is currently taking on a new challenge as Senior Account Manager ll and works closely with the core account teams that manages the day-to-day client relationships. She offers additional support and consultation to help address and resolve specific client needs.