Email Provider — SMTP

Nodemailer SMTP EmailProvider adapter. Node.js only — not compatible with Supabase Edge. Exports createSmtpProvider({ host, port, secure?, auth?, tls? }). secure defaults to true when port === 465. idempotencyKey and correlationId are forwarded as X-Idempotency-Key / X-Correlation-Id headers for observability. Suitable for production SMTP and local dev (Mailhog/Mailpit).