Email Infrastructure Backend Implementation

Architecture

Email functionality is split between two specialized services:

• Resend: Transactional email delivery (high reliability)
• Brevo: Marketing email management (subscriber lists, campaigns)

Service Implementation

ResendService (app/services/resend_service.ts)

export class ResendService {
  static async sendWelcomeEmail(email: string): Promise<void>
  static async sendPasswordReset(email: string, token: string): Promise<void>
  static async sendEventNotification(email: string, event: Event): Promise<void>
}

Features:

• High-deliverability transactional emails
• Template rendering with Edge.js
• Automatic retry logic
• Open/click tracking

BrevoService (app/services/brevo_service.ts)

export class BrevoService {
  static async addSubscriber(email: string, listId: string): Promise<void>
  static async removeSubscriber(email: string, listId: string): Promise<void>
  static async sendCampaign(campaignId: string, recipients: string[]): Promise<void>
}

Features:

• Subscriber list management
• Campaign creation and sending
• Segmentation and targeting
• Analytics and reporting

Email Templates

Template Structure

apps/server/resources/views/emails/
├── welcome.edge          # User welcome email
├── password-reset.edge   # Password reset email
├── event-notification.edge # Event updates
├── newsletter.edge       # Newsletter template
└── layouts/
    └── base.edge         # Base email layout

Template Features

• Responsive design for mobile/desktop
• Consistent Jubiloop branding
• Variable substitution for dynamic content
• GDPR-compliant unsubscribe links
• Analytics tracking pixels

Example Template

<!-- welcome.edge -->
@layout('emails/layouts/base') @section('content')
<h1>Welcome to Jubiloop!</h1>
<p>Hi {{ user.name }},</p>
<p>Thank you for joining Jubiloop. We're excited to help you plan amazing events!</p>
<div class="cta">
  <a href="{{ appUrl }}/dashboard" class="button">Get Started</a>
</div>
@endsection

Environment Configuration

Required Environment Variables

# Resend (Transactional)
RESEND_API_KEY=your_resend_api_key
RESEND_FROM_NAME=Jubiloop Team
RESEND_FROM_EMAIL=noreply@jubiloop.ca

# Brevo (Marketing)
BREVO_API_KEY=your_brevo_api_key
BREVO_NEWSLETTER_SUBSCRIBER_LIST_ID=your_list_id

Per-Environment Settings

• Development: Dev API keys, dev sender addresses
• QA: QA API keys, test recipient lists
• Production: Production API keys, verified domains

Integration Points

Newsletter Subscription Feature

// Uses both services
await BrevoService.addSubscriber(email, listId) // Add to marketing list
await ResendService.sendWelcomeEmail(email) // Send welcome email

Authentication System

// Password reset flow
await ResendService.sendPasswordReset(email, resetToken)

// Welcome new users
await ResendService.sendWelcomeEmail(user.email)

Future Event System

// Event notifications
await ResendService.sendEventNotification(attendee.email, eventData)

// Event marketing
await BrevoService.sendCampaign(campaignId, attendeeEmails)

Security & Compliance

Data Protection

• GDPR Compliance: Unsubscribe links in all marketing emails
• Data Encryption: Secure API communication with TLS
• Access Controls: API keys managed through environment variables
• Audit Logging: Track all email operations for compliance

Security Measures

• Rate Limiting: Prevent abuse of email endpoints
• Input Validation: Sanitize all email addresses and content
• Template Security: Prevent XSS in email templates
• Error Handling: Graceful failure without exposing sensitive data

Monitoring & Analytics

Resend Metrics

• Delivery rate (percentage delivered successfully)
• Open rate (tracking pixel-based)
• Click rate (tracked links)
• Bounce rate (failed deliveries)
• Spam complaints

Brevo Metrics

• Subscriber growth over time
• Campaign engagement rates
• List health (bounce/complaint rates)
• Geographic distribution
• Unsubscribe rates

Health Monitoring

# Test Resend connectivity
curl -H "Authorization: Bearer $RESEND_API_KEY" \
  https://api.resend.com/domains

# Test Brevo connectivity
curl -H "Authorization: Bearer $BREVO_API_KEY" \
  https://api.brevo.com/v3/contacts

Error Handling

Common Failure Scenarios

1. API Rate Limits: Implement exponential backoff
2. Invalid Recipients: Validate email addresses before sending
3. Template Errors: Graceful fallback to plain text
4. Service Outages: Queue emails for retry

Debugging

# Check email service logs
docker logs server | grep -i email

# Test template compilation
# (via AdonisJS REPL or test endpoints)

# Verify API credentials
# (health check endpoints)

Performance Considerations

Optimization Strategies

• Template Caching: Compile templates once, reuse
• Batch Operations: Send multiple emails efficiently
• Async Processing: Queue emails for background processing
• Connection Pooling: Reuse HTTP connections to email APIs

Scalability

• Service Separation: Resend/Brevo handle scaling
• Queue System: Redis-based email queue for high volume
• Retry Logic: Exponential backoff for failed deliveries
• Monitoring: Track performance metrics and alerts

Future Enhancements

Planned Improvements

1. Email Queue System: Async processing with Redis
2. Template Management: Dynamic template updates without deployments
3. A/B Testing: Email variant testing for optimization
4. Advanced Segmentation: Behavioral targeting based on user actions
5. Webhook Integration: Real-time delivery status updates

Integration Opportunities

1. Event Management: Automated event reminder emails
2. User Notifications: In-app to email notification fallback
3. Analytics Integration: Custom email tracking in application analytics
4. Multi-Provider Support: Fallback email providers for reliability