NestJS Mailer Worker

A standalone email microservice built with NestJS, and MongodDB.

Designed for applications that need a centralized email infrastructure with support for multiple email providers, custom templates, email logging, queue processing, and future extensibility.

Overview

NestJS Mailer Worker is a dedicated email service that can be deployed independently from your main application.

Instead of sending emails directly from your API, applications can publish email jobs to this service, allowing reliable, scalable, and observable email delivery.

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GoDaddy Professional Email setup

This worker can send through GoDaddy Professional Email using authenticated SMTP. Add the following values to your local .env or deployment secrets:

MAIL_PROVIDER=smtp
SMTP_HOST=smtpout.secureserver.net
SMTP_PORT=465
SMTP_SECURE=true
SMTP_USER=connect@themealguides.com
SMTP_PASS=your_professional_email_password
SMTP_FROM=connect@themealguides.com

SMTP_PASS is the password for the email mailbox, not the password for your GoDaddy customer account. Keep it in environment secrets and never commit it. For GoDaddy port 465, SMTP_SECURE must be true because the connection uses TLS immediately.

To switch back to the Google API adapter, set MAIL_PROVIDER=gmail and keep the existing Google OAuth variables configured.

The provider can also be selected per request. When omitted, MAIL_PROVIDER is used as the default:

{
  "appId": "meal-guides-api",
  "to": "customer@example.com",
  "subject": "Welcome",
  "html": "<p>Welcome to The Meal Guides.</p>",
  "provider": "smtp"
}

The currently registered request values are smtp and gmail. A provider must have an adapter registered before it can be used.

If Node cannot resolve MongoDB Atlas SRV records on a local machine, set a local-only DNS override. Leave this variable unset in environments whose DNS already works:

DNS_SERVERS=192.168.100.1

Features

Multi-Provider Support

Send emails using different providers:

• SMTP
• Gmail
• Google Workspace
• Microsoft 365
• Outlook
• Custom SMTP Providers
• Future provider integrations

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Custom Email Templates

Create and manage:

• HTML emails
• Plain text emails
• Dynamic variables
• Reusable templates
• Provider-independent templates

Example:

<h1>Welcome {{name}}</h1>
<p>Your account has been created successfully.</p>

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Email Queue Processing

Background email processing using queues.

Benefits:

• Faster API responses
• Retry support
• Failure handling
• High-volume email delivery

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Email Logging

Track every email sent.

Store:

• Recipient
• Subject
• Provider
• Status
• Error messages
• Timestamp

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Delivery Tracking

Monitor email lifecycle:

• Pending
• Processing
• Sent
• Failed
• Retried

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REST API Support

Trigger emails via HTTP endpoints.

Example:

POST /emails/send

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Database Persistence

Powered by Mongodb

Store:

• Templates
• Provider configurations
• Email logs
• Delivery history

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Modular Architecture

Built with NestJS modules.

Easy to extend:

• Add new providers
• Add webhooks
• Add analytics
• Add dashboards
• Add notification channels

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Technology Stack

• NestJS
• TypeScript
• MongoDB
• BullMQ (optional)
• Redis (optional)

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Use Cases

• User registration emails
• Password reset emails
• Verification emails
• Notifications
• Marketing campaigns
• Transactional emails
• Internal system alerts

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Future Roadmap

• Provider failover support
• Email analytics
• Open tracking
• Click tracking
• Webhook integrations
• Template editor
• Admin dashboard
• Multi-tenant support
• Rate limiting
• Scheduled emails

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Why Use This?

Many applications need email capabilities but don't want email logic mixed into the main API.

NestJS Mailer Worker provides a dedicated service responsible for:

• Email delivery
• Provider management
• Logging
• Monitoring
• Reliability

This keeps your core application clean while providing a scalable email infrastructure.

License

MIT