🚀 ColdMailer

ColdMailer is a production-oriented cold email automation system built with Django, Celery, Redis, and PostgreSQL.

The project focuses on scalable backend architecture, asynchronous processing, distributed services, and real-world deployment practices rather than just local development.

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✨ Features

• 📄 Upload resumes for personalized cold email generation
• ⚡ Asynchronous email processing using Celery workers
• 🔁 Automatic retry system for failed emails
• 🧹 Scheduled background jobs using Celery Beat
• 🗂️ Temporary centralized file storage
• 🧠 Designed for multi-service deployment environments
• 📊 Email logging and status tracking
• ☁️ Cloud deployment ready

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🏗️ Architecture

flowchart LR
    U[User / Browser]
    W[Django Web App]
    DB[(PostgreSQL)]
    R[(Redis Broker)]
    CW[Celery Worker]
    CB[Celery Beat]
    FS[(Central File Storage)]
    SMTP[SMTP Provider]

    U -->|Upload resume & inputs| W

    W -->|Store resume temporarily| FS
    W -->|Enqueue async task| R
    W -->|Create email logs| DB

    R -->|Dispatch task| CW
    CW -->|Read resume| FS
    CW -->|Send email| SMTP
    CW -->|Update logs/status| DB

    CB -->|Schedule retries & cleanup| R

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🛠️ Tech Stack

Category	Technology
Backend	Django
Language	Python
Database	PostgreSQL
Queue/Broker	Redis
Async Workers	Celery
Scheduler	Celery Beat
Deployment	Railway
Static Files	WhiteNoise

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📂 Project Structure

coldmailer/
│
├── coldmailer/          # Django project settings
├── mailer/              # Main application logic
├── templates/           # HTML templates
├── static/              # CSS and JS
├── attachments/         # Local development uploads
├── manage.py
└── requirements.txt

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⚙️ Environment Variables

Create a .env file in the root directory.

SECRET_KEY=your_secret_key

DEBUG=True

DATABASE_URL=postgresql://username:password@localhost:5432/coldmailer

REDIS_URL=redis://127.0.0.1:6379/0

SMTP_ENCRYPTION_KEY=your_encryption_key

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🚀 Local Setup

1. Clone Repository

git clone https://github.com/your-username/coldmailer.git
cd coldmailer

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2. Create Virtual Environment

Linux / macOS

python3 -m venv .venv
source .venv/bin/activate

Windows

python -m venv .venv
.venv\Scripts\activate

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3. Install Dependencies

pip install -r requirements.txt

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🧰 Install & Start Redis

Ubuntu

sudo apt update
sudo apt install redis-server

Start Redis:

sudo systemctl start redis-server

Verify Redis:

redis-cli ping

Expected output:

PONG

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🗄️ Setup PostgreSQL

Install PostgreSQL and create a database.

Example:

CREATE DATABASE coldmailer;

Update your DATABASE_URL accordingly.

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🧱 Run Database Migrations

python manage.py migrate

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📦 Collect Static Files

python manage.py collectstatic --noinput

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▶️ Running the Project

Start Django Server

python manage.py runserver

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Start Celery Worker

celery -A coldmailer worker --loglevel=info

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Start Celery Beat

celery -A coldmailer beat --loglevel=info

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🌐 Production Deployment (Railway)

The project is designed to run as multiple services:

• Django Web Service
• Celery Worker
• Celery Beat Scheduler
• Redis
• PostgreSQL

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🚀 Railway Start Command

python manage.py migrate && python manage.py collectstatic --noinput && gunicorn coldmailer.wsgi:application --bind 0.0.0.0:$PORT

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📌 Important Production Notes

• Do not use SQLite in production
• Redis is required for Celery
• PostgreSQL is required for persistent data
• Temporary files should use centralized/shared storage
• Services are stateless and distributed

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📈 Future Improvements

• 🤖 AI-generated personalized emails
• 📊 Analytics dashboard
• 📄 Resume parser
• 🎯 ATS optimization
• 📬 Campaign tracking
• 📑 Email templates
• 🌐 Web Scraper for E-Mails
• 📈 Lead Generation

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🧠 What This Project Demonstrates

This project focuses on:

• Distributed backend systems
• Production deployment
• Asynchronous task queues
• Service-oriented architecture
• Fault tolerance
• Scalability considerations

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👨‍💻 Author

Arjun Tomar

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⭐ Final Note

ColdMailer was built as a backend engineering project to explore how production systems behave beyond local development.

The focus was not only on features, but also on reliability, architecture, deployment, and scalability.