Checking for dead mx hosts

mx.go

package main

import (
	"fmt"
	"net"
	"time"
)

func main() {
	// Set the domain to check
	domain := "example.com"

	// Look up the MX records for the domain
	mxRecords, err := net.LookupMX(domain)
	if err != nil {
		fmt.Println(err)
		return
	}

	// Check each MX record to see if the host is dead
	for _, mx := range mxRecords {
		// Get the host associated with the MX record
		mxHost := mx.Host
		fmt.Printf("Checking MX record for host: %s\n", mxHost)

		// Check if the host is dead
		dead, err := checkDead(mxHost)
		if err != nil {
			fmt.Println(err)
			continue
		}
		if dead {
			fmt.Println("Host is dead")
		} else {
			fmt.Println("Host is alive")
		}
	}
}

// checkDead checks if a host is dead
func checkDead(host string) (bool, error) {
	// Set a timeout for the check
	timeout := time.Second * 5

	// Try to establish a connection to the host
	conn, err := net.DialTimeout("tcp", host+":25", timeout)
	if err != nil {
		// If the connection fails, return true (dead)
		return true, nil
	}
	// If the connection succeeds, close the connection and return false (alive)
	conn.Close()
	return false, nil
}