Best Practices for Email Subject Lines

A successful campaign starts with a subject line that grabs the attention of your subscribers. Good subject lines are often personal or descriptive, and give the recipient a reason to check out your content. Whatever your approach, it's important to keep your audience in mind, and test keywords and phrases to see what they prefer.

In this article, you'll find tips for writing strong subject lines, and learn ways to test subject line performance.

Tips for Subject Lines

Our Research Team analyzes emails sent by users through Mailchimp to find what practices result in the best open rates. Some subject lines have proven to be more successful than others, but there is no tried-and-true strategy that will work for everyone.

The more you test each type of subject line, the more you'll come to know your subscribers and their preferences. Here are a few subject line strategies for you to try out on your subscribers.

Add Personalization

Use merge tags to personalize your subject lines with each recipient's name or location. Personalization is shown to increase open rates for most users, and may work well when combined with targeted automations such as birthday deals and post-purchase follow-ups.

Getting Started With Merge Tags

Merge Tags for Personalization

Be Descriptive

Sometimes, it's better to be direct and descriptive than trendy. Seasonal slogans such as "Fall into savings" or "Sizzling summer bargains" are popular, but don't offer a specific hook. Instead, try to communicate the benefits of your promotions, or call attention to specific deals.

Are Trendy Subject Lines Right for Your Business?

Count Characters

For most users, there is no statistical link between subject line length and open rate. But for subscribers reading your campaigns on mobile devices, shorter may be better.

To find out what works best for your audience, we recommend you look up the top email clients for your audience, and A/B test subject lines of different lengths.

View and Target Subscriber Email Clients: Find Top Email Clients

Create an A/B Testing Campaign

Use Emojis Carefully

Our emoji picker is a fun and easy way to add some visual pizazz to your subject lines, particularly on mobile devices. Different operating systems render different versions of emojis, so it's important to test.

To add emojis to your subject line, follow these steps. Then, use Inbox Preview to see how it'll look to different subscribers.

  1. Navigate to the Campaigns page and open the regular email campaign you want to work with.
  2. In the Subject section, click Add Subject.
    click add subject
  3. In the Subject field, click the smile icon and choose the emojis you want to include.
    click smile icon to pick an emoji

Test Subject Lines

There are a couple of ways to learn whether your subject line is a winner. One is our free subject line researcher tool, which predicts how a word or phrase will perform. You can also use an A/B Testing campaign to see if different subject lines affect your open rates.

Subject Line Researcher

Subject line researcher shows you the effectiveness of different keywords. Search for a word or phrase, and we'll compare your terms to all subject lines ever sent through Mailchimp. Then we'll list related terms and phrases, and use a 5-star rating system to show you how each one performed.

To use the subject line researcher, follow these steps.

  1. Navigate to the Campaigns page and open the regular email campaign you want to work with.
  2. In the Subject section, click Add Subject.
    click add subject
  3. Under the Subject field, click How do I write a good subject line?
    Click How do I write a good subject line
  4. In the pop-up modal, click Subject line researcher.
    click subject line researcher
    To review your previous subject lines and their open rates, click Recent subject line performance.
  5. Type a term or phrase into the Subject line terms field, and click Search. For best results, enter one term or phrase per line, limit phrases to three words, and keep the search broad.
    test subject line terms
  6. Review how your choice of words compares against Adjacent terms/phrases from other Mailchimp campaigns.
    compare subject line terms

A/B Testing Campaigns

A/B Testing campaigns reveal how small differences impact performance. Unlike the subject line researcher, which uses data from campaigns sent by all Mailchimp users, A/B Testing campaigns can tell you what your specific contacts like best.

Create multiple versions of your campaign that are identical in every way but the subject line, and we'll send them to randomly selected parts of your subscribed audience. We'll automatically send the campaign with the best open rate to the remainder of your subscribed audience, and you'll learn a little about what kind of subject line appeals to your contacts.

Create an A/B Testing Campaign

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