A comprehensive SMTP (Simple Mail Transfer Protocol) mail server implementation using Python's smtplib and Flask. This project provides a fully functional email communication system with user authentication, email composition, inbox management, and reply functionality. Built with modern web technologies for seamless email handling in controlled environments.
Why Build an SMTP Server?
The motivation behind this project is to create an efficient SMTP server that can send and receive emails in a controlled and reliable manner. This enables scalable email communication solutions for various applications requiring simple email transmission.
graph TD
A[Email Client] --> B[SMTP Server]
B --> C[Email Processing]
C --> D[Database Storage]
C --> E[Email Delivery]
E --> F[Recipient Inbox]
style A fill:#e1f5fe,stroke:#0277bd,stroke-width:2px
style B fill:#f3e5f5,stroke:#7b1fa2,stroke-width:2px
style F fill:#e8f5e8,stroke:#388e3c,stroke-width:2px
SMTP Server Architecture Overview
| Feature | Description | Status |
|---|---|---|
| 📨 Email Handling | Process and store incoming emails in SQLite database | ✅ Implemented |
| 🔐 User Authentication | Secure login system with duplicate email prevention | ✅ Implemented |
| 📝 Email Composition | Rich email composition with subject and body | ✅ Implemented |
| 📬 Inbox Management | View received emails with sender details | ✅ Implemented |
| 📤 Sent Box | Track all sent emails with timestamps | ✅ Implemented |
| 💬 Reply Functionality | Reply to received emails seamlessly | ✅ Implemented |
| ⭐ Mark Important | Flag important emails for easy access | ✅ Implemented |
| 🗑️ Delete Emails | Remove unwanted emails from inbox/sentbox | ✅ Implemented |
| 📊 Message Parsing | Handle multipart messages and extract content | ✅ Implemented |
| 🔍 Error Handling | Comprehensive logging and error management | ✅ Implemented |
graph TD
A[Frontend] --> B[HTML/CSS/JavaScript]
A --> C[Bootstrap UI]
D[Backend] --> E[Python 3.x]
D --> F[Flask Framework]
D --> G[smtplib]
D --> H[aiosmtpd]
I[Database] --> J[SQLite]
K[Libraries] --> L[email module]
K --> M[sqlite3]
K --> N[logging]
style A fill:#ff9800,color:#fff
style D fill:#2196f3,color:#fff
style I fill:#4caf50,color:#fff
style K fill:#9c27b0,color:#fff
Complete Technology Stack
🐍 Backend Technologies
- Python 3.x: Primary programming language
- Flask: Web framework for creating the user interface
- smtplib: Core SMTP functionality for sending emails
- aiosmtpd: Asynchronous SMTP server implementation
- SQLite: Lightweight database for email storage
🎨 Frontend Technologies
- HTML5/CSS3: Structure and styling
- Bootstrap: Responsive UI framework
- JavaScript: Interactive functionality
sequenceDiagram
participant U as User
participant F as Flask App
participant S as SMTP Server
participant D as Database
participant R as Recipient
U->>F: 1. User Signup/Login
F->>D: 2. Validate Credentials
D-->>F: 3. Authentication Success
U->>F: 4. Compose Email
F->>S: 5. Send Email Request
S->>R: 6. Deliver Email
S->>D: 7. Store in Sent Box
R->>F: 8. Receive Email
F->>D: 9. Store in Inbox
D-->>F: 10. Update Database
Note over U,R: Email Successfully Exchanged
Email Communication Flow
Signup Process
First Signup Accounts to send mail from one account/Gmail to other.
Secure user registration with duplicate email prevention
Compose Email Interface
After logged in, do compose an email on "mudasirnaeem000@gmail.com" Gmail account and sent it to "maisumabbas13@gmail.com"
Clean and intuitive email composition interface
Email Inbox
Email has successfully been sent to "maisumabbas13@gmail.com" and recieved in inbox folder as well. Sent messages has also saved in sentbox.
Organized inbox with sender details and timestamps
Email Reply
We can do a reply as well. Reply emails will sent to the senders mails and sender can review receiver's reply.
Seamless email reply with thread continuity
Reply email has been send to sender's mail, and sender also recieved their reply in inbox folder.
Email Mark as Important
We can delete any email from inbox or sendbox, that may not relevant for us.
We also can mark any email from inbox as important.
Flag important emails for quick access
System Requirements
- Python 3.x installed
- pip package manager
- Local machine for testing
Flask==2.3.3
aiosmtpd==1.4.4
sqlite3 (built-in)
smtplib (built-in)
email (built-in)
logging (built-in)- Navigate to signup page
- Create account with unique email
- Login with credentials
- Click "Compose" button
- Fill recipient, subject, and message
- Click "Send" to deliver email
- View received emails in inbox
- Mark important emails with star
- Reply to emails directly
- Delete unwanted emails
- Access sent box to view outgoing emails
- Check delivery status
- Manage sent email history
| Security Aspect | Implementation | Benefit |
|---|---|---|
| 🔐 User Authentication | Login/Signup system | Prevents unauthorized access |
| 🚫 Duplicate Prevention | Email uniqueness check | Maintains data integrity |
| 📝 Input Validation | Form validation | Prevents malicious inputs |
| 🔍 Error Handling | Comprehensive logging | Tracks system issues |
| 💾 Data Storage | SQLite database | Secure local storage |
erDiagram
USERS {
int id PK
string email UK
string password
datetime created_at
}
EMAILS {
int id PK
string sender FK
string recipient FK
string subject
text body
datetime timestamp
boolean is_important
string status
}
USERS ||--o{ EMAILS : sends
USERS ||--o{ EMAILS : receives
Database Relationship Diagram
📧 Email Processing Module
- Handle incoming/outgoing emails
- Parse email headers and content
- Store emails in database
- Manage email threading
🔐 Authentication Module
- User registration and login
- Password validation
- Session management
- Duplicate email prevention
💾 Database Module
- SQLite database operations
- Email storage and retrieval
- User data management
- Query optimization
🌐 Web Interface Module
- Flask-based web application
- Responsive UI design
- AJAX operations
- User-friendly navigation
gantt
title SMTP Mail Server Development Timeline
dateFormat YYYY-MM-DD
section Phase 1
Research & Setup :done, phase1, 2025-02-21, 2025-03-08
section Phase 2
Core Development :done, phase2, 2025-03-09, 2025-03-20
section Phase 3
Database Integration :done, phase3, 2025-03-21, 2025-04-10
section Phase 4
Testing & Debugging :done, phase4, 2025-04-11, 2025-04-22
section Phase 5
Documentation :done, phase5, 2025-04-23, 2025-05-05
7-Week Development Schedule
| Week | Tasks | Responsibility |
|---|---|---|
| Week 1-2 | Research & Environment Setup | Both Members |
| Week 3 | Email Processing & Server Setup | Mudasir |
| Week 4 | Database Design & Integration | Maisum Abbas |
| Week 5-6 | Testing & Optimization | Both Members |
| Week 7 | Documentation & Submission | Both Members |
🔍 Functional Testing
- Email sending/receiving functionality
- User authentication workflow
- Database operations
- Reply and forward features
🛡️ Security Testing
- Input validation
- SQL injection prevention
- Authentication bypass attempts
- Data encryption verification
⚡ Performance Testing
- Email processing speed
- Database query optimization
- Memory usage monitoring
- Concurrent user handling
mindmap
root((Future Features))
Attachments
File Upload
Image Support
Document Sharing
Security
TLS Encryption
Two-Factor Auth
Spam Filtering
UI/UX
Mobile App
Dark Theme
Rich Text Editor
Integration
API Endpoints
Third-party Services
Cloud Storage
Planned Future Enhancements
| Name | Roll Number | Responsibilities |
|---|---|---|
| Maisum Abbas | 22K-4129 | Flask Integration & Component Integration |
| Mudasir | 22K-8732 | SMTP Server Implementation & Email Handling |
- Python SMTP Library - Core SMTP functionality
- Flask Framework - Web application development
- SQLite Database - Database implementation
- aiosmtpd Library - Asynchronous SMTP server
- SMTP Protocol Specification - RFC 5321
- Email Message Format - RFC 5322
- TLS for SMTP - Secure transmission
- Python Email Module - Message composition
- Postfix Configuration - Mail server setup
- Email Authentication - Security standards
- OpenSSL Documentation - Encryption implementation
- Network: Internet connection for testing
- Operating System: Windows 10/11, macOS, or Linux
- Python: Version 3.7 or higher
- Browser: Chrome, Firefox, Safari, or Edge
- IDE: PyCharm, VS Code, or any text editor
Need Help? Let's Connect! 🌟
📧 Email Support: mudasirnaeem000@gmail.com
🎓 Institution: National University of Computer & Emerging Sciences
📍 Location: Karachi, Pakistan
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** Thank you for exploring our SMTP Mail Server project! **