Write subjects that get opened.

30–55 characters on cold. Mobile clients (where most cold email is first read) clip at around 35–45 characters in the preview pane. Subjects longer than 60 characters lose their tail in the inbox view and underperform in our 100K+ campaign dataset by 18–24% on open rate.

First-name personalization in the subject lifts open rate by an average of 7.2pp on cold across our dataset. Company-name personalization lifts it 11pp. Both together can lift 14pp — but only if the rest of the subject is specific and not a generic template ('Hi {first} — quick question' is template-tell).

On cold B2B: max one, and only if it earns its place. One well-chosen emoji can lift opens 3–5%; two or more drops opens 10–14% in our dataset. Never lead with the emoji — Outlook strips them inconsistently and the subject becomes meaningless.

Real. The model checks length against mobile-clip thresholds, runs the subject against a 200-word spam-trigger library, scores ALL-CAPS and punctuation patterns, detects personalization tokens and sentiment, and weights everything against open-rate outcomes from 100K+ active DitLead campaigns. It runs entirely in your browser.

It's a benchmark for a warmed sender with authenticated domain (SPF/DKIM/DMARC pass) doing cold B2B outbound. If your sender is unwarmed, expect 30–60% of that number until reputation builds. Our warmup network handles that part — your subject handles the rest.

Nothing leaves your browser. The whole analyzer is client-side JavaScript. No logging, no analytics on what you type — period.