MailboxValidator

Connects Claude to the MailboxValidator API for email verification workflows. Exposes three tools: validate_email runs comprehensive checks including syntax, DNS/MX records, greylisting, disposable providers, and suppression lists. check_disposable_email and check_free_email handle those specific lookups. Requires a MailboxValidator API key (free tier gives 300 queries monthly). Reach for this when you need to validate user signups, clean email lists, or filter out temporary addresses in your prompts. Runs via npx with stdio transport, so setup is just adding credentials to your Claude config and restarting.