Email Subject Line Tester

Write subject lines that get opened. Score yours instantly and get actionable tips to improve your open rate.

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Subject Line Best Practices

Optimal Length: 40-60 Characters

Subject lines in this range show the highest open rates across all industries. Mobile screens cut off after ~40 chars.

Use Numbers

Subject lines with numbers get 45% higher open rates. Use specific figures like "3 steps" or "27% increase".

Personalization Tokens

Including {first_name} or {company} can boost open rates by 20-30%. Make readers feel it was written for them.

Avoid Spam Triggers

ALL CAPS, excessive punctuation (!!!), and words like "free", "guaranteed", "act now" hurt deliverability.