In short: A good email subject line is short (about 30 to 50 characters, so it fits on a phone), specific about what's inside, written in normal sentence case with at most one exclamation mark, and free of phrases spam filters and readers distrust, like 'act now', '100% free' or 'you've won'. This checker scores your subject on those rules and shows a phone preview.
What the checker looks at
- Length: phones show roughly the first 35 to 45 characters; desktops about 60.
- Phrases people and filters distrust: "act now", "risk-free", "guaranteed", "you've won", "double your money", "click here" and similar.
- Capitals and punctuation: ALL CAPS and "!!!" read as shouting.
- Money and symbols: big amounts and repeated currency signs.
- Emojis: one can help; several look spammy.
- Fake replies: "Re:" or "Fwd:" on an email that isn't a reply is misleading, and anti-spam laws such as the US CAN-SPAM Act forbid deceptive subject lines.
Words alone don't decide spam
Modern filters at Gmail, Yahoo and Outlook weigh your sending reputation (authentication, bounces, complaints) and how people engage with your emails far more than individual words. A clean list and proper SPF, DKIM and DMARC matter more than avoiding the word "free". This checker is about getting more opens and avoiding obvious red flags. ENB runs a fuller spam check on every campaign before you send, including links, images and authentication. See how to send bulk email without landing in spam.
Subject lines that work for Nigerian businesses
- "New ankara pieces just landed (sizes 8 to 18)"
- "Your December cake order: last day is Friday"
- "{first_name}, your invoice from Ada's Kitchen"
- "3 ways to cut your generator costs this month"
- "Resumption: school fees and dates for second term"
Frequently asked questions
How long should an email subject line be?
Aim for about 30 to 50 characters so the full subject shows on most phones. Put the most important words first.
Which words trigger spam filters?
No single word guarantees spam, but phrases like 'act now', '100% free', 'risk-free' and 'you've won', ALL CAPS and many exclamation marks are classic red flags.
Should I use emojis in subject lines?
One relevant emoji can help a subject stand out. Several look spammy, and some display differently on older phones.
Is my subject line stored?
No. It's checked and the result is returned straight away; we don't keep it.