Last updated: March 2026
Frequently Asked Questions
What makes a good cold email subject line?
Four things correlate with higher open rates: length of 40-60 characters (renders fully on mobile), no spam triggers (free, $$$, ACT NOW), personalization (first name, company name), and curiosity (question, incomplete thought). Avoid emojis in B2B cold outreach — they trigger both spam filters and buyer skepticism.
What's the ideal subject line length?
40-60 characters. Under 40 feels terse and content-less; over 60 truncates on mobile inboxes where ~50% of email is opened. Gmail mobile cuts off around 30-40 chars on small screens, so front-load the hook.
Does this tool guarantee my email lands in the inbox?
No. Subject lines are one factor among many: sender reputation, domain authentication (SPF/DKIM/DMARC), content quality, list hygiene, and engagement history all matter. This tool catches obvious subject-level red flags but can't replace a full deliverability audit.
Should I use emojis in cold emails?
Usually no for B2B cold outreach. Emojis in cold-from-unknown senders feel presumptuous and trigger skepticism. For warm nurture sequences or newsletters to engaged subscribers, emojis can work. This tool flags emoji as a slight negative in the cold context.
Why does 'FREE' hurt my score?
Subject lines containing 'FREE', '$$$', 'ACT NOW', 'GUARANTEE' and similar words historically correlate with spam, so Gmail and Outlook filters give them a spam-score boost. One such word is survivable; two or more often push you into the promotions tab or spam folder.