smtp.go

package main

import (
	"crypto/tls"
	"flag"
	"fmt"
	"log"
	"net"
	"net/mail"
	"net/smtp"
)

// SSL/TLS Email Example

func main() {
	fmt.Println("8u202 | SMTP Check Tool \n")

	usernamePtr := flag.String("username", "", "'string'")
	passwordPtr := flag.String("password", "", "'string'")
	hostPtr := flag.String("host", "", "'string'")
	portPtr := flag.Int("port", 0, "number")
	toPtr := flag.String("to", "", "'string'")

	flag.Parse()

	from := mail.Address{"", *usernamePtr}
	to := mail.Address{"", *toPtr}

	subj := "8u202 | SMTP Check Tool"
	body := "IT WORKS!"

	// Setup headers
	headers := make(map[string]string)
	headers["From"] = from.String()
	headers["To"] = to.String()
	headers["Subject"] = subj

	// Setup message
	message := ""
	for k, v := range headers {
		message += fmt.Sprintf("%s: %s\r\n", k, v)
	}
	message += "\r\n" + body

	// Connect to the SMTP Server
	servername := fmt.Sprintf("%s:%d", *hostPtr, *portPtr)

	host, _, _ := net.SplitHostPort(servername)

	auth := smtp.PlainAuth("", *usernamePtr, *passwordPtr, *hostPtr)

	// TLS config
	tlsconfig := &tls.Config{
		InsecureSkipVerify: true,
		ServerName:         host,
	}

	log.Println("Connecting to server...")

	// Here is the key, you need to call tls.Dial instead of smtp.Dial
	// for smtp servers running on 465 that require an ssl connection
	// from the very beginning (no starttls)
	conn, err := tls.Dial("tcp", servername, tlsconfig)
	if err != nil {
		log.Fatal(err)
	}

	c, err := smtp.NewClient(conn, host)
	if err != nil {
		log.Fatal(err)
	}

	// Auth
	if err = c.Auth(auth); err != nil {
		log.Fatal(err)
	}

	// To && From
	if err = c.Mail(from.Address); err != nil {
		log.Fatal(err)
	}

	if err = c.Rcpt(to.Address); err != nil {
		log.Fatal(err)
	}

	// Data
	w, err := c.Data()
	if err != nil {
		log.Fatal(err)
	}

	_, err = w.Write([]byte(message))
	if err != nil {
		log.Fatal(err)
	}

	err = w.Close()
	if err != nil {
		log.Fatal(err)
	}

	c.Quit()

	fmt.Println("Email Sent Successfully!")

}