javascriptnode.jshttpproxy

Is it possible to connect to a SMTP server through proxy?

I'm attempting to connect to SMTP servers through proxies to validate emails.

I've looked into http-proxy-agent, but as I understand, proxies cannot be used with a TCP connection?

My current connection setup:

const client = net.createConnection(25, mxServer, () => {
                client.write("HELO @mail.com\r\n");
                client.write("MAIL FROM:<email_address>\r\n");
                client.write(`RCPT TO:<${email}>\r\n`);
            });
Solution

  • You should use SOCKS protocol for SMTP connections rather than HTTP proxies since SOCKS work at TCP level. The following is a solution using Node.js with the SOCKS package:

    const SocksClient = require('socks').SocksClient;
const net = require('net');

async function validateEmailThroughProxy(email, mxServer) {
    const socksOptions = {
        proxy: {
            host: 'proxy.example.com', // Your SOCKS proxy host
            port: 1080,               // SOCKS proxy port
            type: 5                   // SOCKS5
        },
        command: 'connect',
        destination: {
            host: mxServer,
            port: 25
        }
    };

    try {
        const info = await SocksClient.createConnection(socksOptions);
        const socket = info.socket;

        // Set encoding for the responses
        socket.setEncoding('utf8');

        // Handle responses
        socket.on('data', (data) => {
            console.log('Received:', data);
        });

        // Send SMTP commands
        socket.write("HELO mail.com\r\n");
        socket.write(`MAIL FROM:<sender@example.com>\r\n`);
        socket.write(`RCPT TO:<${email}>\r\n`);

        // Don't forget to handle closing
        socket.on('close', () => {
            console.log('Connection closed');
        });
    } catch (err) {
        console.error('Error:', err);
    }
}

    Note the following:

    Try the above and see if it solves the problem :-)