# Create subject lines with AI

> Generate subject line options from your email content, then choose and refine the best.

Source: https://www.kualo.com/knowledgebase/mailmachine-campaigns/create-subject-lines-with-ai
Updated: 2026-06-10

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Your subject line is the single biggest influence on whether an email gets opened, and MailMachine's AI can generate options based on the content you've written - so they're relevant rather than generic. This guide covers using it.

## Generate subject lines

1. Create a campaign (see **[Create and send a campaign](/knowledgebase/mailmachine-campaigns/creating-campaigns)**).
2. Design your email content - the AI reads it to suggest subject lines.
3. At the final step of campaign creation, click **Create subject with AI**.
4. You'll get **three options** based on your content.
5. Choose the one you like, or use it as a starting point and tweak it.

## Best practices

- **Review all three** before choosing.
- **Customise** to match your brand voice.
- **Consider your audience** when picking a style.
- **A/B test** the AI's suggestion against your own - see **[Create A/B test campaigns](/knowledgebase/mailmachine-campaigns/create-a-b-test-campaigns)**.

## Why it helps

Content-aware subject lines tend to be more relevant, which lifts open rates; you save the brainstorming time; and quality stays consistent even across lots of campaigns.

A great subject line pairs with a great **[preheader](/knowledgebase/mailmachine-campaigns/write-effective-preheaders)**. To see the effect, watch your **[open rates](/knowledgebase/mailmachine-reporting/understand-open-rates)**. Stuck? [Open a support ticket](/knowledgebase/getting-started/how-to-create-a-support-ticket-in-mykualo).

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_Source: Kualo Knowledgebase — https://www.kualo.com/knowledgebase/mailmachine-campaigns/create-subject-lines-with-ai · © Kualo Ltd._