Email subject line tester for cold email

This free subject line tester evaluates your cold email subject lines against proven deliverability and engagement standards. It checks mobile character truncation, word count, spam words, capitalization, punctuation, and deceptive Re: prefixes to give you an actionable score.

Short, specific and honest about what the email is. A subject that names something real about the reader's business, in a few plain words, tells them why you are writing. Avoid capitals, exclamation marks and promotional phrases, which make a one-to-one email look like a newsletter.

It starts at 100 and subtracts points for each problem on a fixed checklist: length, word count, spam phrases, all-caps words, exclamation marks, fake reply prefixes, money symbols and emoji. Every rule and its weight is listed on this page. It is a checklist, not a prediction of open rate.

Open rates depend mostly on who receives the email and whether they recognise a reason to read it, which no tool can judge from the subject alone. Open tracking is also unreliable since Apple Mail Privacy Protection, so any predicted open rate would be guesswork.

Not on a first email. It pretends a conversation already exists, which misleads the reader, and the US CAN-SPAM Act prohibits deceptive subject lines in commercial email. Use Re: only when you really are replying.

Personalisation helps when it shows you looked at the business, such as its name or something specific about it. Check that every row in your list has a value for the field, or some recipients will see an empty gap or a raw placeholder.