I'm building a mobile app backend and need email delivery infrastructure

Sure — for a mobile app backend, email delivery infrastructure usually means more than just “send emails.” You want:

1. Reliable outbound delivery
2. Authentication and deliverability
3. Tracking and observability
4. Queueing/retries
5. Templates and localization
6. Security and compliance

Recommended architecture

1) Use a dedicated email provider

Common options:

• AWS SES — best for cost and scalability
• SendGrid — good developer experience and templates
• Mailgun — strong API and inbound handling
• Postmark — excellent for transactional emails
• Brevo (Sendinblue) — good all-in-one option

For a mobile app backend, I’d usually recommend:

• Postmark for transactional-only apps
• AWS SES if you want low cost and are comfortable with more setup
• SendGrid if you want easier tooling and dashboards

2) Separate transactional and marketing emails

Keep these in different streams/domains:

• Transactional: password reset, verification, receipts, alerts
• Marketing: newsletters, promos, onboarding campaigns

This helps protect deliverability. If marketing emails get complaints, your critical transactional mail is less affected.

3) Use a dedicated sending domain or subdomain

Examples:

• mail.yourapp.com
• notify.yourapp.com
• mg.yourapp.com

Avoid sending from your root domain if possible. This isolates reputation and reduces risk.

4) Set up email authentication

You should configure:

• SPF
• DKIM
• DMARC

These are essential for deliverability and spoofing protection.

Typical setup:

• SPF authorizes your provider to send on your behalf
• DKIM signs messages cryptographically
• DMARC tells receivers how to handle failed authentication

5) Implement a queue-based sending system

Do not send emails directly in your request/response cycle.

Better flow:

• App/backend triggers email event
• Event goes into queue
• Worker sends through provider
• Retries on transient failures
• Logs success/failure

Use something like:

• SQS + worker
• RabbitMQ
• Redis queue / BullMQ
• Celery
• Sidekiq
• Kafka if you already have it

6) Track delivery events

Enable webhooks from your provider for:

• Delivered
• Bounced
• Complained
• Deferred
• Opened/clicked if needed

Store these in your backend for:

• suppression lists
• analytics
• account health monitoring
• alerting on issues

7) Maintain suppression and bounce handling

Automatically suppress:

• hard bounces
• spam complaints
• unsubscribes
• invalid addresses

This prevents repeated sending to bad addresses and protects your sender reputation.

8) Template system

Use templates for:

• verification emails
• password resets
• welcome emails
• receipts
• security alerts

Best practice:

• keep copy versioned
• support localization
• include plain-text fallback
• use variable substitution safely

9) Security considerations

• Never expose your provider API key in the app
• Send only from your backend
• Rate-limit sensitive emails like verification and password reset
• Add anti-abuse controls for account creation and email flooding
• Use signed, expiring links for actions like verification/reset

10) Monitoring and alerting

Monitor:

• send rate
• bounce rate
• complaint rate
• provider errors
• queue backlog
• webhook failures

Set alerts for:

• spike in bounces
• queue buildup
• SMTP/API failures
• DMARC failures if you track them

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Example backend flow for verification email

1. User signs up in mobile app
2. Backend creates account with email_verified = false
3. Backend generates signed token
4. Backend publishes send_verification_email job
5. Worker sends via provider
6. Provider returns message ID
7. Webhook updates status later
8. User clicks verification link
9. Backend verifies token and marks email verified

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Suggested minimal production stack

If you want something practical and fast to launch:

• Provider: Postmark or AWS SES
• Queue: SQS, BullMQ, or Sidekiq
• Templates: provider-managed or app-managed templates
• Webhooks: for bounce/complaint/delivery events
• Domain: notify.yourapp.com
• Auth: SPF + DKIM + DMARC
• Monitoring: CloudWatch, Datadog, or similar

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If you want, I can help you with one of these next:

1. Choose the best provider for your use case
2. Design the backend email architecture
3. Set up SPF/DKIM/DMARC
4. Write code examples in Node.js, Python, Go, or Java
5. Design a transactional email service for your app

If you tell me your stack and expected email volume, I can recommend a concrete setup.