AI subject line and preheader generator

Writing a subject line after you have just finished building an entire email can feel like an afterthought. The AI subject line and preheader generator helps you get past that blank-page moment by suggesting combinations based on a description of your email content. You choose from the suggestions, adjust as needed, and apply them to your campaign in one click.

This feature is available without limits on all subscription plans.

How to use the generator

Step 1: Open the generator

The generator is accessible from the first step of the campaign wizard, where you set your subject line and preheader.

1. Start creating a campaign and go to step 1.
2. Find the subject line field.
3. Click the Suggest button next to the subject line field. This opens the generator in a popup.

Step 2: Describe your email

The generator needs context to produce useful suggestions. In the description field, write a short summary of your email. The more specific you are, the better the suggestions will be.

A good description covers three things:

• The main message of the email. What is it about?
• The call to action. What do you want the reader to do?
• Your audience. Who are you sending this to?

Example: "We are launching a new line of running shoes for women. The email highlights the lightweight design and includes a 15% launch discount. Audience: existing female customers who have bought running gear before."

Step 3: Choose a tone and purpose

Select a tone and a purpose from the two dropdowns. These guide the style and intent of the suggestions.

Available tones include: formal, casual, friendly, humorous, inspirational, motivational, urgent, informative, promotional, persuasive, conversational, storytelling, mysterious, and thought-provoking.

Available purposes include: promotional, informational, transactional, educational, engaging, relationship-building, retention, lead nurturing, event promotion, product launch, customer support, community-building, onboarding, and seasonal or holiday-themed.

Step 4: Generate suggestions

Click Generate. The generator produces six suggestion cards. Each card shows a sender name preview, a subject line, and a preheader, so you can see exactly how the combination would appear in an inbox.

Step 5: Review and select

You have several ways to work with the suggestions:

• Select a full card. This picks both the subject line and preheader from that card at once.
• Iterate. If you want to keep some cards and replace others, select the cards you want to keep and click Iterate. The generator replaces the unselected cards with new suggestions while keeping your selections in place.
• Regenerate. If none of the suggestions work, click Regenerate to produce a completely new set. This uses another round of tokens.

Step 6: Apply to your campaign

Once you are happy with your selection, click Use these. The subject line and preheader fields in your campaign wizard are filled in automatically. You can still edit them manually before sending.

Getting better suggestions

The quality of the suggestions depends heavily on the quality of your description. A vague description produces generic results.

Common mistakes to avoid

• Using the suggestions without reviewing them. The generator produces starting points, not finished copy. Always read the suggestions carefully and edit them to match your exact offer and tone.
• Regenerating repeatedly without changing the description. If the first set of suggestions misses the mark, the issue is usually the description. Refine it before generating again.
• Ignoring the preheader suggestions. The generator creates subject line and preheader pairs designed to work together. Using a generated subject line alongside a hastily written preheader misses part of the value.
• Treating AI output as final. Subject lines with specific numbers, deadlines, or personalisation that you add manually will often outperform a purely generated suggestion. Use the generator to get unstuck, then make it your own.

Next steps

• See "What makes a good subject line?" for guidance on what makes a subject line work, which will help you evaluate and improve the suggestions the generator produces.
• See "Writing a preheader" to understand what makes a good preheader if you want to write or edit one manually.
• Set up AB testing to compare a generated subject line against one you wrote yourself. Over time this tells you how much value the generator adds for your specific audience.