Email Subject-Line A/B Testing
Systematically A/B test email subject lines across retention campaigns to maximize open rates, from manual 5-test smoke runs through autonomous AI-driven optimization that finds and maintains the local maximum for every lifecycle email.
npx gtm-skills add product/retain/email-subject-testingOutcome
5 subject-line tests completed with documented open-rate data per variant
Leading Indicators
- Open rate per variant
- Click rate per variant
- Unsubscribe rate per variant
Instructions
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Select 5 retention emails from active Loops sequences or broadcasts (re-engagement, feature announcement, renewal, usage summary, tips).
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Record each email's current subject line and historical open rate from Loops as the control baseline.
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For each email, write 1 subject-line variant using a different framing dimension: (1) personalization, (2) curiosity gap, (3) social proof, (4) direct value, (5) urgency. Keep the email body identical.
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Configure each test in Loops: send variant A to 50% and variant B to 50% of the segment. Wait 48 hours per test.
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After 48 hours, pull open rate, click rate, and unsubscribe rate per variant from Loops.
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Record results in a structured log: test number, email type, control subject + open rate, variant subject + open rate, framing category, winner (or tie if <3pp difference).
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Evaluate: pass threshold is 5 tests completed with per-variant open-rate data recorded. If pass, document which framing categories performed best and proceed to Baseline.
Recommendations
Time
5 hours over 1 week
Play-specific cost
Free