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Create subject lines with AI

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

1 min read Updated 10 Jun 2026

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).
  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.

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. To see the effect, watch your open rates. Stuck? Open a support ticket.

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