Test your email subject lines instantly — get an open rate score, spam word detection, character count analysis, and actionable suggestions. No signup, no login.
Enter the subject line you plan to use. The preview shows exactly how it appears in a mobile inbox, including truncation.
Your subject gets an overall score out of 100 based on length, spam words, emotional words, emoji usage, and inbox preview.
Fix spam words, optimise character count, add or remove emojis, and use the tips to write a subject line that gets opened.
Research consistently shows that 40–60 characters is the sweet spot for most audiences. Mobile email clients typically show 30–40 characters on the inbox preview, so place the most important words first. Gmail shows roughly 77 characters on desktop but only 30 on mobile. Shorter subjects (under 40 chars) often outperform longer ones.
Used sparingly (1–2 per subject), emojis can increase open rates by 5–25% by making your email stand out in a crowded inbox. Overuse has the opposite effect. Not all email clients render emojis identically — test with your audience. B2B audiences are generally more conservative than B2C.
Common spam trigger words include: FREE, GUARANTEED, WINNER, CASH, CLICK HERE, LIMITED TIME, ACT NOW, EARN MONEY, NO COST, RISK FREE. All-caps words are also flagged. Modern spam filters use ML models, not just word lists — but avoiding these words still reduces the risk of landing in spam or promotions tab.
