Most AI agents can't send or receive email. RegalMail fixes that. It's an npm plugin that connects any AI agent to a real email inbox via IMAP IDLE (instant inbound) and SMTP (outbound with proper threading). Thread-aware replies. Message-ID/In-Reply-To headers. Anti-loop protection blocks noreply addresses and rate-limits per sender. Works with Gmail, Outlook, OCI, Fastmail, or any IMAP/SMTP provider. Free tier: 1 mailbox, 200 emails/mo. Install with npm install regalmail.