AI Subject Line Generator

Generate multiple subject line variants with AI

AI Subject Line Generator

The AI Subject Line Generator creates multiple subject line options for your campaign, complete with style labels. Instead of spending time brainstorming, let the AI produce a variety of options and pick the one that resonates best.

How to Generate Subject Lines

1. In the campaign builder, go to the Setup step or click Subject Lines in the Mailnaptic AI toolbar.
2. The generator opens. If your campaign already has content, the AI uses it as context. Otherwise, you can provide a brief description of the email's topic.
3. Click Generate Subject Lines.
4. The AI returns 5 or more subject line variants, each labeled with a style tag such as:
   • Curiosity — piques interest without giving everything away.
   • Direct — clearly states the email's value proposition.
   • Urgency — creates a sense of time pressure.
   • Personal — uses a conversational, one-to-one tone.
   • Question — engages the reader with a question.
   • Benefit-led — leads with the main benefit to the reader.
5. Click on any generated subject line to select it. It is automatically inserted into the subject line field.
6. You can regenerate for a fresh batch or edit the selected subject line manually.

Tips for Better Results

• The more context the AI has, the better the subject lines. Write your email content before generating subject lines, or provide a detailed brief.
• Use the generated subject lines as inspiration. You can edit and combine elements from multiple suggestions.
• After selecting a subject line, use the AI Subject Line Scoring tool to evaluate it and get improvement suggestions.
• Keep subject lines under 50 characters for best mobile rendering. The generator aims for this length but you should verify.
• Avoid all-caps and excessive punctuation in subject lines — these can trigger spam filters.

AI Credit Usage

Each generation request (producing a batch of subject lines) consumes one AI credit. Regenerating produces a new batch and consumes an additional credit.