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

At the minimum, you need:

1. An email-sending provider

   • Examples: SendGrid, Postmark, Amazon SES, Mailgun, Resend.
   • This is the actual service that delivers mail.

2. A domain you control

   • Used so emails come from something like noreply@yourapp.com.
   • Helps deliverability and looks more trustworthy.

3. DNS authentication records

   • Usually:
     • SPF
     • DKIM
     • DMARC
   • These prove to inbox providers that your app is allowed to send mail.

4. A sending address

   • e.g. noreply@, support@, or hello@.
   • Often best to use a dedicated subdomain like mail.yourapp.com.

5. Templates for transactional messages

   • Password reset
   • Email verification
   • Receipt / invoice
   • Alert / notification
   • Keep them simple and branded.

6. An app-side send mechanism

   • Usually a small service, job queue, or background worker that calls the provider’s API.
   • Avoid sending directly in request/response if reliability matters.

7. A way to handle bounce/failure events

   • Webhooks or provider event logs.
   • Lets you detect invalid addresses and delivery problems.

8. Basic logging/monitoring

   • Record message ID, recipient, template type, status, and errors.
   • Useful for debugging support issues.

Bare-minimum MVP version

If you want the absolute smallest workable setup:

• One provider
• One verified domain
• SPF + DKIM
• One sending address
• One API integration
• A few templates

Strongly recommended but not strictly required

• DMARC
• Bounce/complaint handling
• A dedicated sending subdomain
• Rate limiting and retries
• Unsubscribe handling for any non-transactional messages

If you want, I can turn this into a practical launch checklist or recommend the simplest stack for a small SaaS.