Detect and block spearphishing emails that use personalized, researched content to evade generic spam filters, by configuring email security gateway (SEG) impersonation protection, URL rewriting, attachment sandboxing, and custom detection rules in Microsoft Defender for Office 365, Proofpoint, Mimecast, or Barracuda.
Install
npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill detecting-spearphishing-with-email-gatewaynpx skills add mukul975/Anthropic-Cybersecurity-Skills --skill detecting-spearphishing-with-email-gateway -a claude-code -gnpx skills add mukul975/Anthropic-Cybersecurity-Skills --skill detecting-spearphishing-with-email-gateway -a codex -ggemini skills install https://github.com/mukul975/Anthropic-Cybersecurity-Skills.git --path skills/detecting-spearphishing-with-email-gatewaygh skill install mukul975/Anthropic-Cybersecurity-Skills detecting-spearphishing-with-email-gatewaygit clone --depth 1 https://github.com/mukul975/Anthropic-Cybersecurity-Skills /tmp/mukul975__Anthropic-Cybersecurity-Skills
mkdir -p ~/.claude/skills ~/.agents/skills
cp -R /tmp/mukul975__Anthropic-Cybersecurity-Skills/skills/detecting-spearphishing-with-email-gateway ~/.claude/skills/detecting-spearphishing-with-email-gateway # Claude Code
cp -R /tmp/mukul975__Anthropic-Cybersecurity-Skills/skills/detecting-spearphishing-with-email-gateway ~/.agents/skills/detecting-spearphishing-with-email-gateway # Codex, Cursor, Gemini CLI, Copilot, OpenCode