使用 Office 365 设置标准 Go net/smtp 失败并显示 "Error tls: first record does not look like a TLS handshake"

Question

我正在尝试使用默认的 Go 包创建一个简单的 Go 电子邮件服务 net/smtp - 我知道有 gomailer，但我想使用标准库

我需要帮助配置 tls/server 设置以与 Office365

一起使用

我相信我有正确的主机：

smtp.office365.com:587

但是，通过复制 Microsoft 提供的 smtp 文档，当 运行 以下代码时，我的控制台出现以下错误：

错误：tls：第一条记录看起来不像是 TLS 握手 恐慌：运行时错误：无效内存地址或零指针解引用

package main

import (
"fmt"
"net"
mail "net/mail"
smtp "net/smtp"
)

func main() {

from := mail.Address{"", "example@example.com"}
to := mail.Address{"", "example@example.com"}
subject := "My test subject"
body := "Test email body"

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

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

servername := "smtp.office365.com:587"
host, _, _ := net.SplitHostPort(servername)

auth := smtp.PlainAuth("", "example@example.com", "password", host)

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

conn, err := tls.Dial("tcp", "smtp.office365.com:587", tlsconfig)
if err != nil {
    fmt.Println("tls.Dial Error: %s", err)
}

c, err := smtp.NewClient(conn, host)
if err != nil {
    fmt.Println("smtp.NewClient Error: %s", err)
}

if err = c.Auth(auth); err != nil {
    fmt.Println("c.Auth Error: %s", err)
}

if err = c.Mail(from.Address); err != nil {
    fmt.Println("c.Mail Error: %s", err)
}

if err = c.Rcpt(to.Address); err != nil {
    fmt.Println("c.Rcpt Error: %s", err)
}

w, err := c.Data()
if err != nil {
    fmt.Println("c.Data Error: %s", err)
}

_, err = w.Write([]byte(message))
if err != nil {
    fmt.Println("Error: %s", err)
}

err = w.Close()
if err != nil {
    fmt.Println("reader Error: %s", err)
}

c.Quit()
}

O365 客户端的任何示例都将受到赞赏，或者任何人都能发现的可疑内容都很棒

谢谢

Answer 1

错误消息 Error: tls: first record does not look like a TLS handshake 告诉您问题所在 :-)。如果您尝试连接到服务器，您将看到（与任何 SMTP 服务器一样）它使用纯文本：

telnet smtp.office365.com 587
Trying 2603:1026:c0b:10::2...
Connected to zrh-efz.ms-acdc.office.com.
Escape character is '^]'.
220 ZRAP278CA0003.outlook.office365.com Microsoft ESMTP MAIL Service ready at Mon, 11 Nov 2019 17:13:50 +0000
...

您需要使用 STARTTLS 命令，请参阅 https://en.wikipedia.org/wiki/Opportunistic_TLS（以及该 wiki 页面指向的 RFC）。

在 Go 中，它是 https://golang.org/pkg/net/smtp/#Client.StartTLS。

我注意到你的代码

tlsconfig := &tls.Config{
    InsecureSkipVerify: true,   <== REMOVE THIS
    ServerName:         host,
}

请删除 InsecureSkipVerify，顾名思义，它是不安全的，与您遇到的错误无关。

Answer 2

所以问题全在于授权。首先要求我在客户端使用 StartTLS 方法，还要求我编写一个函数和方法来支持登录，这是标准 Go 库不支持的（无论出于何种原因）

查看main()上面的函数和结构

这是完整的代码，带有辅助功能，现在可以通过我的 O365 帐户成功发送电子邮件：

package main

import (
"fmt"
"net"
"errors"
mail "net/mail"
smtp "net/smtp"
)

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("Unknown fromServer")
        }
    }
    return nil, nil
}

func main() {

from := mail.Address{"", "example@example.com"}
to := mail.Address{"", "example@example.com"}
subject := "My test subject"
body := "Test email body"

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

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

tlsconfig := &tls.Config{
    ServerName:         host,
}

conn, err := tls.Dial("tcp", "smtp.office365.com:587", tlsconfig)
if err != nil {
    fmt.Println("tls.Dial Error: ", err)
}

c, err := smtp.NewClient(conn, host)
if err != nil {
    fmt.Println("smtp.NewClient Error: ", err)
}


if err = c.Auth(LoginAuth("example@example.com", "password")); err != nil {
        fmt.Println("c.Auth Error: ", err)
        return
}

if err = c.Mail(from.Address); err != nil {
    fmt.Println("c.Mail Error: ", err)
}

if err = c.Rcpt(to.Address); err != nil {
    fmt.Println("c.Rcpt Error: ", err)
}

w, err := c.Data()
if err != nil {
    fmt.Println("c.Data Error: ", err)
}

_, err = w.Write([]byte(message))
if err != nil {
    fmt.Println("Error: ", err)
}

err = w.Close()
if err != nil {
    fmt.Println("reader Error: ", err)
}

c.Quit()
}

Answer 3

1. Outlook.com 自 2017 年 8 月起不再支持 AUTH PLAIN 身份验证。

https://support.microsoft.com/en-us/office/outlook-com-no-longer-supports-auth-plain-authentication-07f7d5e9-1697-465f-84d2-4513d4ff0145?ui=en-us&rs=en-us&ad=us

2. 使用授权登录

以下代码实现AUTH LOGIN

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(a.username), 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("Unknown from server")
        }
    }
    return nil, nil
}

3. 删除“InsecureSkipVerify: true”

tlsconfig := &tls.Config {
    ServerName: host,
}

4. 不要使用tsl.Dial()，使用net.Dial()

conn, err := net.Dial("tcp", "smtp.office365.com:587")
if err != nil {
    return err
}

5. 在 smtp.NewClient()
之后调用 StartTLS()

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

if err = c.StartTLS(tlsconfig); err != nil {
    return err
}

6. 使用授权登录

auth := LoginAuth(fromAddress, password) 

if err = c.Auth(auth); err != nil {
    return err
}

Answer 4

以下对我来说效果很好：

package main

import (
    "bytes"
    "crypto/tls"
    "errors"
    "fmt"
    "net"
    "net/smtp"
    "text/template"
)

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(a.username), 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("Unknown from server")
        }
    }
    return nil, nil
}

func main() {

    // Sender data.
    from := "O365 logging name"
    password := "O365 logging pasword"

    // Receiver email address.
    to := []string{
        "receiver email",
    }

    // smtp server configuration.
    smtpHost := "smtp.office365.com"
    smtpPort := "587"

    conn, err := net.Dial("tcp", "smtp.office365.com:587")
    if err != nil {
        println(err)
    }

    c, err := smtp.NewClient(conn, smtpHost)
    if err != nil {
        println(err)
    }

    tlsconfig := &tls.Config{
        ServerName: smtpHost,
    }

    if err = c.StartTLS(tlsconfig); err != nil {
        println(err)
    }

    auth := LoginAuth(from, password)

    if err = c.Auth(auth); err != nil {
        println(err)
    }

    t, _ := template.ParseFiles("template.html")

    var body bytes.Buffer

    mimeHeaders := "MIME-version: 1.0;\nContent-Type: text/html; charset=\"UTF-8\";\n\n"
    body.Write([]byte(fmt.Sprintf("Subject: This is a test subject \n%s\n\n", mimeHeaders)))

    t.Execute(&body, struct {
        Name    string
        Message string
    }{
        Name:    "Hasan Yousef",
        Message: "This is a test message in a HTML template",
    })

    // Sending email.
    err = smtp.SendMail(smtpHost+":"+smtpPort, auth, from, to, body.Bytes())
    if err != nil {
        fmt.Println(err)
        return
    }
    fmt.Println("Email Sent!")
}

使用以下模板作为奖励:)

<!-- template.html -->
<!DOCTYPE html>
<html>
<body>
    <h3>Name:</h3><span>{{.Name}}</span><br/><br/>
    <h3>Email:</h3><span>{{.Message}}</span><br/>
</body>
</html>