Golang STMP Without TLS

main.go.md

Script GoLang SMTP without TLS, used to test Postal Mail Server

package main

import (
	"crypto/tls"
	"errors"
	"log"
	"net/smtp"

	"gopkg.in/gomail.v2"
)

const CONFIG_SMTP_HOST = "<host>"
const CONFIG_SMTP_PORT = 587
const CONFIG_SENDER_NAME = "<[email protected]"
const CONFIG_AUTH_EMAIL = "<tokenname>"
const CONFIG_AUTH_PASSWORD = "<tokenkey>"

type loginAuth struct {
	username, password string
}

func LoginAuth(username, password string) smtp.Auth {
	return &loginAuth{username, password}
}

func (a *loginAuth) Start(server *smtp.ServerInfo) (string, []byte, error) {
	return "LOGIN", []byte{}, nil
}

func (a *loginAuth) Next(fromServer []byte, more bool) ([]byte, error) {
	if more {
		switch string(fromServer) {
		case "Username:":
			return []byte(a.username), nil
		case "Password:":
			return []byte(a.password), nil
		default:
			return nil, errors.New("Unkown fromServer")
		}
	}
	return nil, nil
}

func main() {
    mailer := gomail.NewMessage()
    mailer.SetHeader("From", CONFIG_SENDER_NAME)
    mailer.SetHeader("To", "[email protected]")
    mailer.SetHeader("Subject", "Test mail")
    mailer.SetBody("text/html", "Hello, <b>have a nice day</b>")

    dialer := gomail.NewDialer(
        CONFIG_SMTP_HOST,
        CONFIG_SMTP_PORT,
        CONFIG_AUTH_EMAIL,
        CONFIG_AUTH_PASSWORD,
    )

	  dialer.TLSConfig = &tls.Config{InsecureSkipVerify: false}

    // tweak tls
    auth := LoginAuth(CONFIG_AUTH_EMAIL, CONFIG_AUTH_PASSWORD)
    dialer.Auth = auth
  
    err := dialer.DialAndSend(mailer)
    if err != nil {
        log.Fatal(err.Error())
    }

    log.Println("Mail sent!")
}