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Email subject tester

Test your email subject line before sending: get a 0 to 100 score on length, spam triggers, personalization and readability, plus concrete fixes.

Test a subject line

Type or paste your subject line. It is scored as you type.

Score
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Enter a subject to test
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What the score measures

The score blends seven checks email marketers actually use: character length, word count, spam-trigger words, all-caps shouting, exclamation mark abuse, personalization signals and scannability. Each failed check costs 12 points, so a subject failing three checks lands around 64, which matches how picky inbox filters are.

Why 50 characters is the magic number

Most mobile email apps cut subject lines around 40 to 50 characters. Desktop Gmail shows about 70. Writing under 50 guarantees your full message and your call to action survive on the smallest screen, which is where most opens happen.

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Email Subject Tester FAQs

What words trigger spam filters?
Classic triggers include free, guaranteed, winner, cash prize, act now, risk-free and no cost, plus ALL CAPS and multiple exclamation marks. Filters score combinations, so one mild word is fine but three together is risky.
Does personalization really lift open rates?
Yes. Subject lines with the recipient's name or a relevant you-phrase consistently outperform generic ones by 20 to 30 percent in most industry studies. Relevance beats cleverness in the inbox.
How long should a subject line be?
20 to 50 characters, or 3 to 10 words. Shorter than 20 often lacks a clear promise; longer than 50 gets truncated on phones and dilutes the message.
Should I use emojis in subject lines?
One relevant emoji can lift opens in B2C, but they render inconsistently across email clients and can trip strict corporate filters. Test with your audience before making them a habit.
How many exclamation marks are too many?
More than one. A single exclamation mark is acceptable for genuine excitement; two or more reads as spam to both filters and humans. When in doubt, use a period or nothing.
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