Email Integration Documentation - DeployStack - Enterprise Control Plane for MCP

This document describes the email system integration in DeployStack, including the email service, template system, and recommended usage patterns.

Overview

The email system provides a comprehensive solution for sending templated emails using:

Background Job Queue: Async email processing with automatic retry (Recommended)
Nodemailer: For SMTP email delivery
Pug Templates: For beautiful, maintainable email templates
Global Settings Integration: Automatic SMTP configuration from global settings
Template Caching: Performance optimization for template rendering

Recommended: Sending Emails via Background Jobs

For all user-facing email operations, use the background job queue instead of direct email sending.

The background job approach provides significant benefits over direct email sending:

Why Background Jobs?

Performance Benefits:

Instant Response: API endpoints return immediately without waiting for SMTP operations
Non-Blocking: Email sending doesn’t delay critical user flows like registration or password reset
Scalability: Can queue hundreds of emails without impacting application performance

Reliability Benefits:

Automatic Retry: Failed emails automatically retry with exponential backoff (3 attempts by default)
Error Isolation: Email failures don’t crash user-facing operations
Rate Limiting: Built-in support for respecting SMTP server rate limits

Observability Benefits:

Job Tracking: All email operations tracked in the job queue database
Comprehensive Logging: Full logging of email operations, successes, and failures
Status Monitoring: Query job status and history for debugging

Background Job Usage

// RECOMMENDED: Queue email as background job
await server.jobQueueService.createJob('send_email', {
  to: 'user@example.com',
  subject: 'Welcome to DeployStack',
  template: 'welcome',
  variables: {
    userName: 'John Doe',
    userEmail: 'user@example.com',
    loginUrl: 'https://cloud.deploystack.io/login'
  }
});

// Job is queued and returns immediately
// Email will be sent by background worker within seconds

Real-World Example: Registration Flow

// In registration route - after user created successfully
const jobQueueService = (server as any).jobQueueService;
if (jobQueueService) {
  await jobQueueService.createJob('send_email', {
    to: user.email,
    subject: 'Verify Your Email Address',
    template: 'email-verification',
    variables: {
      userName: user.username,
      userEmail: user.email,
      verificationUrl: `https://cloud.deploystack.io/verify?token=${token}`,
      expirationTime: '24 hours'
    }
  });
  server.log.info(`Verification email queued for ${user.email}`);
}

// Registration completes instantly
// Email sent by worker in background

When to Use Background Jobs

Use background jobs for:

User registration/verification emails
Password reset emails
Welcome emails
Notification emails
Batch email operations
Any email that doesn’t require immediate confirmation

Monitoring Background Jobs

// Check job status in database
const jobs = await db.select()
  .from(queueJobs)
  .where(eq(queueJobs.type, 'send_email'))
  .orderBy(desc(queueJobs.created_at))
  .limit(10);

// Job statuses: 'pending', 'processing', 'completed', 'failed'

For complete details on the job queue system, see the Background Job Queue Documentation.

Direct Email Sending (Advanced)

Direct email sending is only recommended for specific use cases requiring immediate feedback.

When to Use Direct Sending

Use EmailService.sendEmail() directly only for:

Test Emails: Admin panel SMTP testing requiring immediate success/failure feedback
Synchronous Validation: Flows where you must confirm email sent before proceeding
Development/Debugging: Local testing and troubleshooting

Direct Usage Example

import { EmailService } from '../email';

// Direct sending - blocks until complete
const result = await EmailService.sendEmail({
  to: 'admin@example.com',
  subject: 'SMTP Test Email',
  template: 'test',
  variables: {
    testDateTime: new Date().toISOString(),
    adminUser: 'Admin',
    appUrl: 'https://cloud.deploystack.io'
  }
}, request.log);

if (result.success) {
  request.log.info('Email sent successfully');
  return { success: true, messageId: result.messageId };
} else {
  request.log.error('Failed to send email:', result.error);
  return { success: false, error: result.error };
}

Performance Consideration

Direct email sending adds 2-5 seconds of latency to your endpoint. This is acceptable for admin testing but not acceptable for user-facing operations like registration.

Architecture

src/email/
├── emailService.ts       # Main email service with SMTP integration
├── templateRenderer.ts   # Pug template compilation and rendering
├── types.ts             # TypeScript interfaces and schemas
├── index.ts             # Module exports
└── templates/
    ├── layouts/
    │   ├── base.pug     # Main email layout
    │   ├── header.pug   # Email header component
    │   └── footer.pug   # Email footer component
    ├── welcome.pug              # Welcome email template
    ├── email-verification.pug   # Email verification template
    ├── password-reset.pug       # Password reset template
    ├── password-changed.pug     # Password change notification
    ├── notification.pug         # General notification template
    └── test.pug                 # SMTP test template

src/workers/
└── emailWorker.ts       # Background job worker for emails

SMTP Configuration

The email system automatically integrates with SMTP global settings. Configure these settings in the admin panel or global settings:

Setting	Required	Description
`smtp.enabled`	✅	Enable/disable email sending system-wide
`smtp.host`	✅	SMTP server hostname (e.g., smtp.gmail.com)
`smtp.port`	✅	SMTP server port (587 for TLS, 465 for SSL)
`smtp.username`	✅	SMTP authentication username
`smtp.password`	✅	SMTP authentication password (encrypted)
`smtp.secure`	❌	Use SSL/TLS connection (default: true)
`smtp.from_name`	❌	Default sender name (default: DeployStack)
`smtp.from_email`	❌	Default sender email (default: username)

Template System

Available Templates

Template	Description	Required Variables
`welcome`	Welcome email for new users	`userName`, `userEmail`, `loginUrl`
`email-verification`	Email address verification	`userName`, `userEmail`, `verificationUrl`, `expirationTime`
`password-reset`	Password reset instructions	`userName`, `resetUrl`, `expirationTime`
`password-changed`	Password change notification	`userEmail`, `changeTime`
`notification`	General notification template	`title`, `message`
`test`	SMTP configuration testing	`testDateTime`, `adminUser`, `appUrl`

Template Variables

All templates have access to these common variables:

currentYear: Current year (automatically injected)
appName: Application name (default: ‘DeployStack’)
supportEmail: Support email address (if provided)

Custom Templates

To create custom templates:

Add new Pug template in src/email/templates/
Add TypeScript types in src/email/types.ts
Use with background jobs or EmailService.sendEmail()

Color Guidelines

When adding colors to email templates, follow the official DeployStack color system to maintain brand consistency. See the UI Design System page for color specifications.

Advanced Email Options

Both background jobs and direct sending support advanced options:

await jobQueueService.createJob('send_email', {
  to: 'user@example.com',
  subject: 'Important Notification',
  template: 'notification',
  variables: { title: 'Update', message: 'New features available' },
  
  // Advanced options
  from: {
    name: 'DeployStack Support',
    email: 'support@deploystack.io'
  },
  replyTo: 'support@deploystack.io',
  cc: ['admin@deploystack.io'],
  bcc: ['archive@deploystack.io'],
  attachments: [{
    filename: 'guide.pdf',
    content: pdfBuffer,
    contentType: 'application/pdf'
  }]
});

Utility Methods

Test SMTP Connection

const status = await EmailService.testConnection(request.log);
if (status.success) {
  request.log.info('SMTP connection successful');
} else {
  request.log.error('SMTP connection failed:', status.error);
}

Other Utilities

getSmtpStatus() - Check SMTP configuration status
refreshConfiguration() - Reload SMTP configuration
getAvailableTemplates() - Get list of available templates
validateTemplate() - Validate template and variables

Error Handling

Background Job Errors

Background jobs automatically retry on failure:

Attempt 1: Immediate execution
Attempt 2: After 1 second (if first fails)
Attempt 3: After 2 seconds (if second fails)
Final: Job marked as ‘failed’ after 3 attempts

Check failed jobs in the database:

SELECT * FROM queue_jobs 
WHERE type = 'send_email' 
  AND status = 'failed'
ORDER BY created_at DESC;

Direct Sending Errors

Direct sending provides immediate error feedback:

const result = await EmailService.sendEmail(options, logger);
if (!result.success) {
  // Handle errors immediately
  logger.error(`Email failed: ${result.error}`);
  
  // Common errors:
  // - 'SMTP not configured'
  // - 'Invalid email address'
  // - 'Connection timeout'
  // - 'Authentication failed'
}

Security & Performance

Security Features

Passwords encrypted in global settings
Secure connections (TLS/SSL) supported
Template security with escaped variable injection
No sensitive data in job queue payload

Performance Features

Template caching after first compilation
Connection pooling (max 5 concurrent connections)
Rate limiting (5 emails per 20 seconds)
Background processing doesn’t block main thread

Migration Guide

Converting Existing Code to Background Jobs

Before (Blocking):

const result = await EmailService.sendWelcomeEmail({
  to: user.email,
  userName: user.name,
  userEmail: user.email,
  loginUrl: 'https://cloud.deploystack.io/login'
}, request.log);

After (Non-Blocking):

await server.jobQueueService.createJob('send_email', {
  to: user.email,
  subject: 'Welcome to DeployStack',
  template: 'welcome',
  variables: {
    userName: user.name,
    userEmail: user.email,
    loginUrl: 'https://cloud.deploystack.io/login'
  }
});

Common Usage Patterns

User Registration

Queue verification email as background job immediately after user creation.

Password Reset

Queue password reset email with secure token link.

System Notifications

Queue notification emails for system events, deployments, or status changes.

Batch Operations

Queue multiple emails with rate limiting to avoid SMTP throttling:

for (let i = 0; i < users.length; i++) {
  await jobQueueService.createJob('send_email', {
    to: users[i].email,
    subject: 'Monthly Newsletter',
    template: 'notification',
    variables: { ... }
  }, {
    scheduledFor: new Date(Date.now() + (i * 1000)) // 1 second apart
  });
}

API Reference

EmailService Methods

Method	Description	Returns
`sendEmail(options, logger)`	Send an email directly using a template	`Promise<EmailSendResult>`
`testConnection(logger)`	Test SMTP connection	`Promise<{success: boolean, error?: string}>`
`getSmtpStatus()`	Check SMTP configuration status	`Promise<{configured: boolean, error?: string}>`
`refreshConfiguration()`	Reload SMTP configuration	`Promise<void>`
`getAvailableTemplates()`	Get list of available templates	`string[]`
`validateTemplate(template, variables)`	Validate template and variables	`Promise<TemplateValidationResult>`

Job Queue Service Methods

Method	Description	Returns
`createJob(type, payload, options?)`	Create a background job	`Promise<Job>`
`getJobStatus(jobId)`	Get job status and details	`Promise<Job>`

Background Job Queue - Complete job queue system documentation
Global Settings - SMTP and system configuration
API Documentation - REST API patterns and standards

Summary

For all user-facing email operations, use background jobs. This provides instant response times, automatic retry, and better reliability. Reserve direct EmailService.sendEmail() calls for admin testing and debugging scenarios requiring immediate feedback.

​Overview

​Recommended: Sending Emails via Background Jobs

​Why Background Jobs?

​Background Job Usage

​Real-World Example: Registration Flow

​When to Use Background Jobs

​Monitoring Background Jobs

​Direct Email Sending (Advanced)

​When to Use Direct Sending

​Direct Usage Example

​Performance Consideration

​Architecture

​SMTP Configuration

​Template System

​Available Templates

​Template Variables

​Custom Templates

​Color Guidelines

​Advanced Email Options

​Utility Methods

​Test SMTP Connection

​Other Utilities

​Error Handling

​Background Job Errors

​Direct Sending Errors

​Security & Performance

​Security Features

​Performance Features

​Migration Guide

​Converting Existing Code to Background Jobs

​Common Usage Patterns

​User Registration

​Password Reset

​System Notifications

​Batch Operations

​API Reference

​EmailService Methods

​Job Queue Service Methods

​Related Documentation

​Summary

Overview

Recommended: Sending Emails via Background Jobs

Why Background Jobs?

Background Job Usage

Real-World Example: Registration Flow

When to Use Background Jobs

Monitoring Background Jobs

Direct Email Sending (Advanced)

When to Use Direct Sending

Direct Usage Example

Performance Consideration

Architecture

SMTP Configuration

Template System

Available Templates

Template Variables

Custom Templates

Color Guidelines

Advanced Email Options

Utility Methods

Test SMTP Connection

Other Utilities

Error Handling

Background Job Errors

Direct Sending Errors

Security & Performance

Security Features

Performance Features

Migration Guide

Converting Existing Code to Background Jobs

Common Usage Patterns

User Registration

Password Reset

System Notifications

Batch Operations

API Reference

EmailService Methods

Job Queue Service Methods

Related Documentation

Summary