10 Tips for Improving Your Subject Line

Email users receive plenty of marketing emails from senders every day, and their decision to either open, delete, or ignore messages happens in a fraction of a second. The mountain of information filling up their inboxes, therefore, forces them to only read what they consider relevant or eye-catching.

So, how do you get users to click on your message?

By optimizing your subject lines. The subject line is the most important factor of the open rate, and testing different subject lines and measuring their effectiveness on your open rate is essential to any effective email campaign.

Here are 10 tips for creating successful subject lines:

1. Personalization: Inserting your customer’s name in the subject line makes them feel special, gives your brand credibility, and creates a stronger sense of engagement with them. But you can go even further. Use the data you have collected from your users to personalize your subject line to the max—reference what team they support, their gender, their location, etc.

But personalization should be used in moderation. If you insert a user’s name in every email campaign you send to them, it will not draw the attention it once did because your personalization will become ubiquitous. Also, make sure you have all the necessary data of your users because it is possible for your subject line to show as “Unknown User, Happy Birthday!”.

Using the user’s name in a Birthday campaign is a good example of personalization

2. Stimulating customers’ curiosity, asking questions, or compelling users to discover additional information by opening your emails are other ways to increase open rates. Using words that create a sense of urgency also perform well too.

3. Leverage pre-headers to complement your subject line. Personalize them as well, and also, don’t leave your message without a pre-header because it will end up looking strange (see examples below).

Bad example of personalization: a message with no pre-header


Good example of a personalized pre-header

4. Sender Name: Some companies’ use sender names like “John from E-commerceX” to create intimacy with users, but using your brand name is the best option. Your brand is most likely recognized by all of your subscribers, and usually, users have no idea who John is.

5. Length: Keep your subject lines short. Don’t use long subject lines because mailbox providers will cut them short, making only the beginning of your subject lines visible. This is also important when your email is being opened on mobile. The best recommendation for the length of your subject lines is 41-50 characters and never more than 70.

6. Conduct a benchmark against your competitors or with other companies that use optimized subject lines. Return Path can help you do this with their Subject Line Optimizer tool, which compares your subject line against competitors who use similar keywords in their subject lines. The tool also shows the effectiveness of your competitors’ subject lines by displaying the read rates of each of their campaigns.

7. Use special characters and numbers: Emojis, hearts, stars, etc. are positively perceived by users and grab their attention when they scan their inboxes. These special characters almost always positively impact open rates.

8. Use keywords like discount, sale, etc. In the past, these keywords could negatively impact your deliverability, sending your messages to the spam folder. But nowadays, mailbox providers consider engagement between users and brands the most valuable determinant for spam filtering, so your subject line will not affect your sender reputation.

9. Voice and tone: Align your email communication with your brand voice. If your brand is more on the informal side, it’s okay to use slang in your subject lines. If customers consider your company a luxury brand, err on the side of cordiality, staying consistent with the value your brand conveys. In short, communicate how your audience communicates.

10. Always Be TestingA/B testing subject lines is an underutilized email marketing tactic and needs to be further explored by companies. These tests are so valuable because by implementing them you can access sharpened visibility into who your users actually are and measure the effectiveness of your subject line. You can measure the results of your tests by comparing open rates, clicks, clicks per open, and even conversions.

There is no magic formula for optimizing your subject lines, so always be testing and find out what works best for your business and audience. Good luck!

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