FREE email subject line tester | Subject line checker online tool
Test your email subject lines with our FREE tool.
Paste in your subject lines, and get instant analysis to help you improve your open rates.
By signing up to our free tools you will also receive occasional emails from MailNinja. Of course, you can opt-out at any time.

Here’s the 11 things we check…

1. Word & character count.
Why is this important?
The recommendation by Mailchimp, is to keep your subject lines to no more than 9 words and 60 characters.
2. Spam words.
Why is this important?
Known spammy words can mean your email doesn’t reach inboxes, which is not awesome.


3. Action verbs.
Why is this important?
Action words like Get, Do, Try and Make are all powerful and action-orientated words to help drive a positive response.
4. Listicle.
Why is this important?
Everyone loves a list, try adding things like ‘9 ways to…’ or ‘the top 7 tips for…’ to help boost your open rates.


5. Case.
Why is this important?
Studies show using ALL CAPS is bad, lower and Sentence case is ok. Instead, try Title Case for better results.
6. Sentiment.
Why is this important?
A nice positive message stands out from the crowd. Try to write in. a positive tone, not a negative one.


7. Perspective verbs.
Why is this important?
Writing from your perspective doesn’t resonate with your audience, try writing from their point of view, like ‘Check MY subject line’, not check YOUR, for example.
8. Adverbs.
Why is this important?
An adverb is an action or a doing word, which can help your readers to use their imagination. Try using an adverb for your subject lines, and check the results.


9. Question.
Why is this important?
Studies show, that by asking a question, you increase open rates. A question can help prompt a response from your audience.
10. Emojis.
Why is this important?
Smart use of emojis in your email subject lines can help make your email stand out in a crowded inbox.


11. Filler words.
Why is this important?
The main objective is to reduce the words you use to say something. So by removing filler words, you make your subject lines pop!