Question 1

How does the email subject line tester work?

Accepted Answer

The tool analyzes your email subject line against 10 weighted criteria: length (30-60 characters), spam words, excessive capitalization, punctuation, emojis, personalization ({first_name}), numbers, power words, question format, and word count. You get a score out of 100 with specific recommendations for each criterion.

Question 2

What is the ideal length for an email subject line?

Accepted Answer

Between 30 and 60 characters. Below 30, the subject lacks context to convince. Beyond 60, it gets cut off on mobile — and 60% of emails are opened on smartphones. The sweet spot is between 40 and 50 characters for maximum open rates.

Question 3

What spam trigger words should I avoid in email subject lines?

Accepted Answer

Words like "free", "urgent", "limited offer", "click here", "promotion", "win", "100%" trigger spam filters in Gmail, Outlook, and Yahoo. Our tester automatically detects these words and suggests alternatives.

Question 4

Do emojis improve email open rates?

Accepted Answer

1 to 2 well-placed emojis can increase open rates by 5 to 10% according to studies. Beyond 2, the effect reverses: the email looks like spam. The tester checks emoji count and alerts you if there are too many.

Question 5

How can I increase my email open rate?

Accepted Answer

Personalize the subject with the recipient's first name (+26% open rate), ask a curiosity-sparking question, use concrete numbers ("5 mistakes to avoid"), and avoid spam trigger words. Test every subject line with our tool before sending — it's free and instant.

Question 6

Is my data sent to a server?

Accepted Answer

No. The analysis runs entirely in your browser, client-side. No email subject line is sent, stored, or analyzed server-side. Your data stays 100% private. No signup required.

Free Email Subject Line Tester

Newsletters that convert, on autopilot

Frequently Asked Questions