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How we grade your subject line
Our grader evaluates five dimensions that consistently separate high-performing cold email subject lines from ones that go unread.
L
Length
The ideal subject line is 4-8 words and 20-50 characters. Over 80 characters and mobile clips it before your hook lands.
P
Personalization
Using the recipient's name or company makes the email feel 1:1 instead of broadcast. This alone can lift opens 20-30%.
S
Specificity
Numbers and percentages signal substance. "Save 3 hours a week" outperforms "save time" because it's credible and concrete.
R
Spam Risk
Words like "free", "guaranteed", and "act now" train spam filters and make humans distrust the email immediately.
C
Curiosity
Questions and curiosity-gap openers ("Why most cold emails...") create an open loop that compels people to click through.