What are the minimum pieces I need for transactional email infrastructure in a new app?

For a new app, the minimum pieces you need for transactional email infrastructure are:

1. A Transactional Email Provider: This is non-negotiable—you need a service (like Postmark, SendGrid, Mailgun, Amazon SES, Resend, or Notify) to actually deliver the emails.
2. A Verified Domain: This ensures your emails come from your own domain (e.g., noreply@yourdomain.com) and not a shared one, which is critical for deliverability and legitimacy. Domain verification typically involves setting up SPF, DKIM, and DMARC DNS records.
3. DNS Records: Configure SPF, DKIM, and DMARC for your domain to authenticate your emails and prevent spoofing or spam filtering.
4. A Sending Address: A dedicated email address (e.g., noreply@yourdomain.com) for sending transactional emails.
5. Content for Emails: The actual email content (subject, body, etc.) that you want to send.
6. A Trigger Mechanism: A way to trigger the email send from your app (e.g., via API call or SMTP relay).
7. Bounce/Webhook Handling (Recommended): Set up webhooks to automatically receive notifications for bounces, deliveries, or failures, so your app can react (e.g., retry or log errors) without manual intervention.

These are the core components to get started. For most small teams, using a lightweight transactional email API (like Notify or Resend) will cover all of these with minimal setup.