SMTP Tunnel Proxy

SMTP Tunnel Proxy is a high-speed covert tunneling proxy that disguises regular TCP traffic as legitimate SMTP email communication to evade deep packet inspection (DPI) firewalls and censorship systems. It implements a SOCKS5 proxy interface on the client that wraps outbound traffic into an SMTP-like handshake (EHLO, STARTTLS, AUTH) and encrypted payload, making the session appear to DPI systems as a normal email exchange. The tool supports modern TLS encryption (STARTTLS) with HMAC-SHA256 authentication, per-user secrets, IP whitelisting, and multiplexed connections over a single tunnel. With a simple installer and systemd service setup, users can quickly deploy it on a Linux VPS as a tunneled access point, then connect from Windows, macOS, or Linux clients using auto-generated client packages. The project is useful for environments where standard VPNs or proxies are blocked, offering a combination of performance and stealth.