Result
5 to check
38% capitals · 0 emoji · 3 “!”
- LengthCheck44 characters — fine on desktop, but phones often show only the first ~40. Put the key words first.
- Spam-trigger wordsCheckFound: “free”. One word rarely gets an email filtered on its own, but these phrases add up with other signals.
- Capital lettersCheck38% capitals, 2 words in ALL CAPS. Keep capitals for one short word at most.
- PunctuationCheck3 exclamation marks — one is plenty.
- EmojiGoodNo emoji.
- Preview textCheckNo preview text. Without it, inboxes show the first words of the email (often “View in browser”). Add a line that continues the subject.
What the checker looks at
- Length. Phones often show roughly the first 40 characters, desktops more. Long subjects get cut off — put the point first.
- Spam-trigger phrases. Words like “free”, “act now”, “limited time”, “winner”, “cash” and “guarantee” are common in spam. They won't block an email alone, but they add up with other signals.
- Capital letters. A subject in ALL CAPS reads as shouting and is a classic spam signal. One capitalised word for emphasis is plenty.
- Punctuation. Two or more exclamation marks look pushy.
- Emoji. One can help; several clutter the line and render differently from inbox to inbox.
- Preview text. Without it, inboxes show whatever text comes first in the email.
Writing better subject lines
- Be specific. “New linen shirts, in 6 colours” tells people what's inside; “Big news!” doesn't.
- Match the email. A subject that over-promises earns unsubscribes and complaints, which hurt deliverability far more than any word.
- Personalise with care. A first name can help, but always set a fallback for contacts without one — in Trisend,
{{first_name|there}}. - Test two versions. An A/B test sends two subjects to a sample and the rest get the winner.
Trisend's email builder runs these checks — plus missing alt text, buttons without links and image-only emails — in the review step before every campaign. A/B subject tests are on the Starter plan and up.
Frequently asked questions
How long should an email subject line be?
There's no single limit, because every inbox shows a different amount. Desktop inboxes often show 60–70 characters; phones often show around 40. Keeping the important words at the start matters more than hitting an exact number. The checker warns above 40 and flags anything over 70.
Will one spam word send my email to spam?
Almost never on its own. Modern filters weigh many signals — your sending reputation, authentication (SPF, DKIM, DMARC), how recipients engage, and the content. Spam-style phrases, ALL CAPS and lots of exclamation marks add to the score, so it's worth avoiding them where a plainer word works.
Should I use emoji in subject lines?
One relevant emoji can help a subject stand out, but emoji render differently across devices and several in a row look cluttered. Test on your own phone first.
What is preview text?
The short line many inboxes show next to or below the subject. If you don't set it, the inbox shows the first text in the email instead — often “View in browser”. Use it to continue the subject.
Is my subject line stored or sent anywhere?
No. The checker runs entirely in your browser.
More guides & tools
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