Senior Full-Stack Developer (SMTP Infrastructure & Email Verification)

Project Overview
We are looking for a seasoned developer to audit, finalize, and package a high-performance Bulk Email Verifier and SMTP Sender. The system uses a "Master-Proxy" architecture to perform deep SMTP pings while remaining invisible to recipient mail servers.
Key Technical Responsibilities
• Stealth SMTP Engineering: Audit and refine the "Deep SMTP Ping" logic to ensure the handshake terminates immediately after the RCPT TO command to maintain 100% anonymity.
• Identity Masking: Implement a randomized sender engine that rotates official and organic prefixes (e.g., admin@, sarah@) paired with burner domains to bypass ISP throttling.
• SOCKS5 Networking: Ensure the verification engine strictly utilizes SOCKS5 proxies to bypass Port 25 blocks common in hosting environments.
• Security & Licensing: Build a Master License Server to validate purchase codes, track global installs, and implement a remote "Kill Switch" for pirated copies.
• Data Safety: Finalize the "Danger Zone" Factory Reset and Backup/Restore utilities using PDO transactions for 100% data integrity.
• System Diagnostics: Refine the System Health Check utility to verify Port 25 status, PHP extensions, and folder permissions.
Commercial & Deployment Deliverables
• Auto-Updater: Configure GitHub Actions for one-click updates from the client Admin Dashboard.
• Stripe Integration: Build a private sales website for VPS/Installation services with Stripe payment processing.
• CodeCanyon Packaging: Organize the final codebase into a submission-ready ZIP with full documentation (HTML/PDF).
• Live Sandbox: Set up and host a functional "Sandbox" demo of the platform for potential buyers.
• Marketing Assets: Produce a 3–5 minute professional video demo and high-quality product screenshots.
Required Skills
• Backend: Expert PHP (PDO, Sockets), Python (FastAPI/Pandas for reporting), and Node.js.
• Database: Advanced MySQL/PostgreSQL (Transactions, Truncation, JSON exports).
• Frontend: Bootstrap 5 for clean, responsive Admin Dashboards.
• DevOps: Docker, GitHub Actions, Linux Networking (IP Tables/Routing).
• Experience: Prior work with SMTP protocols, mail server reputation, or email marketing infrastructure.

Mandatory Deliverables (The "Sales Package"):
• Professional Video Demo: A 3–5 minute high-quality screen recording with voiceover (or professional captions) demonstrating the setup, Excel integration, and mobile connection.
• Complete Documentation: A professional HTML/PDF "User & Developer Manual" covering installation, API usage, and troubleshooting.
• The CodeCanyon Zip: A perfectly organized folder ready for submission.
• Website like this sample of my:
https://mediaxtremebulksms.com/
Since we are giving exclusive distribution rights to CodeCanyon, at this site
we sell only VPS and Installation services for new customers.
[Installation services will be provided by you. We need to agree to the fee
to be charged. You keep 70%, after payment processer % fee per transaction]
• Payment processing using Stripe
• Use provided logo, site-icon and html code for website design, including Terms and Policy [provided to you]
• The Live Demo Site: Set up and host a functional "Sandbox" version of the platform for potential buyers to test (with simulated sending). Using the same from website design.
• Screenshots for our CodeCanyon product page
• Update logo in the existing dashboard. You will use the same for the website.

I will supply the architecture and logic codes necessary.

This platform is not a standard web app; it is a high-performance networking tool that requires expertise in asynchronous PHP, SMTP protocols, and SOCKS5 proxy management.
Based on the system's architecture, here are the mandatory Technical Requirements you should ask your developer to meet:
1. Advanced Networking & Stealth SMTP Knowledge
The developer must understand how to keep the Master Server anonymous through specific handshake techniques.
• Deep SMTP Pinging: Ability to implement a handshake that terminates with the QUIT command immediately after the RCPT TO response to remain invisible in recipient history.
• Identity Randomization: Proficiency in building a "Randomized Sender" engine that rotates prefixes (e.g., admin@, noreply@) and matches them with configured "Burner Domains".
• SOCKS5 Proxy Integration: Mastery of routing traffic through SOCKS5 proxies to bypass Port 25 blocks common in hosting environments.
2. High-Performance "10x" Speed Optimization
To achieve a massive increase in verification speed, the developer needs experience with parallel processing.
• Multi-Process Control (PCNTL): Experience using pcntl_fork to spawn multiple "child" workers that process lead list segments simultaneously.
• Asynchronous Sockets: Skill in setting sockets to non-blocking mode (stream_set_blocking) so workers don't "hang" while waiting for slow mail server responses.
• Bulk Database Operations: Ability to implement bulk "Upserts" (Update or Insert) for results (e.g., buffering 500 leads at a time) to prevent database locking during high-speed runs.
3. Security & Licensing Infrastructure
Since the platform is intended for CodeCanyon and private VPS sales, it requires a robust protection layer.
• Master License Server: Building a central API to validate purchase codes and track global installations.
• Remote Kill Switch: Implementing a secure mechanism to disable access to pirated or unauthorized copies of the script.
• Secure Password Recovery: Implementing time-sensitive reset tokens stored in the database for secure admin access.
4. Administrative & "Danger Zone" Logic
The developer must build tools that allow the user to manage their environment safely.
• System Health Check: A diagnostic utility that verifies PHP 8.1+ requirements, folder permissions (e.g., /logs), and Port 25 availability.
• Factory Reset Security: Implementation of a double-confirmation "Danger Zone" where users must type "RESET" before the script truncates data tables.
• Automated Backups: Logic to export settings, proxies, and lists into a portable JSON format for easy restoration.
5. Commercial Deployment & Auto-Updates
To scale the business, the developer must handle the "Sales Package" requirements.
• GitHub Actions Integration: Configuring workflows so users can update their platform with a single click from their dashboard.
• Stripe Integration: Setting up payment processing for VPS and installation services.
• Live Sandbox Environment: Setting up a functional "Demo" site with automated 24-hour data wipes.