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SalarsNet
📧AI Email Marketing Engine

AI-Based Subject Line Testing That Improves Open Rates Automatically

Use AI to generate and iterate subject lines based on performance data, while maintaining authenticity and aligning opens with conversions.

Quick Answer

For search, voice, and "just tell me what to do".

Generate subject line families, test one variable at a time, and feed results back into an evolving library of what works for your audience.

Key Takeaways:

  • Open rates matter-but only if clicks and sales follow.
  • Test one variable: curiosity vs clarity, short vs long, benefit vs story.
  • Build a swipe file of winners and the rules behind them.
  • Avoid spam triggers and overhyped language.

Playbook

1

Pick 3 subject line styles you want to test (curiosity, benefit, personal).

2

Ask AI for 20 variants per style with strict constraints.

3

A/B test on a consistent segment and send time.

4

Track opens + clicks + conversions, not opens alone.

5

Save winners and repeat monthly with refinements.

Common Pitfalls

  • Optimizing for opens while trust declines.
  • Changing too many variables at once.
  • Using clickbait that doesn't match the email content.

Metrics to Track

Open rate

Click rate

Conversion rate

Spam complaints

FAQ

How many subject lines should I test?

Start with one A/B test per send. Over time, you'll accumulate enough data to know which styles consistently win for your list.

Should I personalize subject lines with names?

Sometimes. It depends on your audience. Test it, but don't assume it's better-often clarity or curiosity performs best.

What's the best subject line length?

There's no universal best. Many lists respond well to 4–7 word lines, but test against your own data and device mix.

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Salarsu - Consciousness, AI, & Wisdom | Randy Salars