golang net/smtp SMTP AUTH LOGIN Auth Handler

smtp_login_auth.go

// MIT license (c) andelf 2013


import (
	"net/smtp"
	"errors"
)

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
}


// usage: 
// auth := LoginAuth("loginname", "password")
// err := smtp.SendMail(smtpServer + ":25", auth, fromAddress, toAddresses, []byte(message))
// or	
// client, err := smtp.Dial(smtpServer)
// client.Auth(LoginAuth("loginname", "password"))

Microsoft has permanently disabled Basic Authentication in Exchange Online (Microsoft 365), you will receive the next message "Authentication unsuccessful, basic authentication is disabled".

Unfortunately this code no longer work, it's mandatory implement OAuth 2.0 or another method accepted by Microsoft