Use when capturing outbound email in development or staging without delivering to real recipients, inspecting HTML or headers, running spam or structure checks, or automating tests against a fake inbox. Use when testing outgoing mail from an app without committing to a production ESP yet. Use when using Mailtrap Email Sandbox, Sandbox API, or sandbox-mode sending.
Install
npx skills add mailtrap/mailtrap-skills --skill testing-with-sandboxnpx skills add mailtrap/mailtrap-skills --skill testing-with-sandbox -a claude-code -gnpx skills add mailtrap/mailtrap-skills --skill testing-with-sandbox -a codex -ggemini skills install https://github.com/mailtrap/mailtrap-skills.git --path skills/testing-with-sandboxgh skill install mailtrap/mailtrap-skills testing-with-sandboxgit clone --depth 1 https://github.com/mailtrap/mailtrap-skills /tmp/mailtrap__mailtrap-skills
mkdir -p ~/.claude/skills ~/.agents/skills
cp -R /tmp/mailtrap__mailtrap-skills/skills/testing-with-sandbox ~/.claude/skills/testing-with-sandbox # Claude Code
cp -R /tmp/mailtrap__mailtrap-skills/skills/testing-with-sandbox ~/.agents/skills/testing-with-sandbox # Codex, Cursor, Gemini CLI, Copilot, OpenCode