SimpleEmailServer

A simple client-server based email simulation system built using Java, demonstrating TCP/IP socket programming, Object-Oriented Programming (OOP), Dependency Injection, and Database operations (SQLite). The project allows users to register, login, send emails, and optionally generate email bodies using a Python ML model.

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Features

• Send and receive emails using a TCP/IP-based custom protocol.
• User registration and login stored in an SQLite database.
• Inbox and Sent email management using database tables.
• Automatic email body generation using a Python ML model based on subject keywords.
• Modular code structure with OOP principles and dependency injection.

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Technologies Used

Technology	Purpose
Java	Core programming language
TCP/IP Sockets	Network communication between client and server
SQLite	Database to store user credentials and emails
Python (ML)	Generates email body based on subject
OOP Concepts	Encapsulation, modular design, class-based structure
Dependency Injection	Decoupling email server from database instance

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Project Structure

SimpleEmailServer/
│
├
├── Main.java                 # Client CLI for registration, login, and sending emails
│── SimpleEmailServer.java    # Handles sending emails via TCP socket and calls Python ML for email body
│── User.java                 # User model
│── Database.java             # SQLite DB handler
│── DatabaseCopy.java         # Wrapper for Database with DI
│── EmailReceiverServer.java  # TCP Server to receive emails and store them
│
├── ml_models/                    # Python ML model for email body generation
│   ├── predict_email.py
│   ├── email_vectorizer.pkl
|   ├── train_email_model.py
│   └── email_nn_model.pkl
│
├── users.db                      # SQLite database storing credentials & emails
├── README.md                     # Project documentation
└── ...

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How It Works

1. Registration

   • User registers with name, email, and password.
   • Credentials are stored in the SQLite database.

2. Sending an Email

   • Client collects from, to, subject, and optionally generates body using Python ML.
   • If ML body is not available or user rejects it, client can enter a custom body.
   • Sends data using a TCP socket to the server.
   • Email is inserted into Sent table and delivered to the receiver.

3. Receiving an Email

   • Server listens on port 5000.
   • Accepts email data from client and stores it in the Inbox table of the database.

4. Dependency Injection

   • SimpleEmailServer receives a DatabaseCopy instance via its constructor.
   • Promotes loose coupling and easier testing.

5. ML Email Body Generation

   • Python script ml_models/predict_email.py uses a pre-trained model to generate a suggested email body based on subject keywords.
   • User can accept or override the generated email body.

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Getting Started

Prerequisites

• Java JDK 8 or higher installed.
• VS Code or any Java IDE.
• SQLite (optional, to inspect the database).
• Python 3.x with scikit-learn and pickle installed (for ML model).

Compile Java Code

javac src/*.java

Run the Server

java -cp <path> EmailReceiverServer

Run the Client (in a separate terminal)

java -cp <path> Main

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Example Inbox Output (Database Query)

Querying the Inbox table after sending an email:

mail_from	name	subject	message
Anjali	Nidhi	Greetings	Hi, hope you're doing well!
Anjali	John	Welcome	Welcome to our platform!

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Notes

• This is a simulation and does not send real emails over the internet.
• All data is stored in a local SQLite database.
• Demonstrates TCP/IP networking, OOP, Dependency Injection, and Python ML integration for generating email bodies.

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