Generates, scores, and split-tests email subject lines, producing angle-distinct variants, a numeric scorecard, and a test plan with sample size and decision metric. Covers B2B cold outbound and B2C lifecycle/promotional email, and flags spam-trigger words inside the subject line only.
Install
npx skills add mbfinotti/sales-skills --skill cold-email-subject-line-testernpx skills add mbfinotti/sales-skills --skill cold-email-subject-line-tester -a claude-code -gnpx skills add mbfinotti/sales-skills --skill cold-email-subject-line-tester -a codex -ggemini skills install https://github.com/mbfinotti/sales-skills.git --path skills/cold-email-subject-line-testergh skill install mbfinotti/sales-skills cold-email-subject-line-testergit clone --depth 1 https://github.com/mbfinotti/sales-skills /tmp/mbfinotti__sales-skills
mkdir -p ~/.claude/skills ~/.agents/skills
cp -R /tmp/mbfinotti__sales-skills/skills/cold-email-subject-line-tester ~/.claude/skills/cold-email-subject-line-tester # Claude Code
cp -R /tmp/mbfinotti__sales-skills/skills/cold-email-subject-line-tester ~/.agents/skills/cold-email-subject-line-tester # Codex, Cursor, Gemini CLI, Copilot, OpenCode