Django配置Gmail发送邮件失败求助：已开启两步验证仍无法发送

我用Django开发在线作品集，其中包含联系表单功能。测试阶段用MailTrap验证功能正常，但切换到生产环境想让邮件发送至Gmail邮箱时始终失败，只有MailTrap能正常工作。

我的Gmail账户已开启两步验证，并创建了应用专用密码（低安全性选项自今年5月起已不存在）。

Settings.py配置 #

EMAIL_BACKEND = 'django.core.mail.backends.smtp.EmailBackend'
EMAIL_HOST = "smtp.gmail.com"
EMAIL_HOST_USER = "my-e-mail@gmail.com"
EMAIL_HOST_PASSWORD = 'smbumqjiurmqrywn'  # 示例密码，仅展示格式
EMAIL_PORT = 587
EMAIL_USE_TLS = True

邮件发送视图代码 #

注：使用EmailMessage或send_mail结果一致

def contact(request):
    contact_form = ContactForm()

    if request.method == 'POST':
        contact_form = ContactForm(data = request.POST)

        if contact_form.is_valid():
            name = request.POST.get('name', '')
            email = request.POST.get('email', '')
            content = request.POST.get('content', '')

            # 发送邮件
            email = EmailMessage(
                'New message from {} <{}>'.format(name, email),
                'From {} <{}>\n\nWrote:\n\n{}'.format(name, email, content),
                email,
                [settings.EMAIL_HOST_USER]
            )
            
            email.send()
            
    return render(request, 'core/contact.html', {'form' : contact_form})

异常情况 #

• 仅修改Settings.py凭证为MailTrap即可正常工作，Gmail配置每次都会进入except块
• 多次尝试发送后，Gmail应用专用密码的「最近使用」栏为空

报错信息 #

Environment:

Request Method: POST
Request URL: http://127.0.0.1:8000/contact-me/

Django Version: 3.2.7
Python Version: 3.9.6
Installed Applications:
['django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'core',
 'portfolio.apps.PortfolioConfig']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware']

Traceback (most recent call last):
  File "C:\Python\Python39\lib\site-packages\django\core\handlers\exception.py", line 47, in inner
    response = get_response(request)
  File "C:\Python\Python39\lib\site-packages\django\core\handlers\base.py", line 181, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "C:\Users\PC CASE Gerardo\OneDrive\Documents\Proyectos\Python\webpersonal\core\views.py", line 34, in contact
    email.send()
  File "C:\Python\Python39\lib\site-packages\django\core\mail\message.py", line 284, in send
    return self.get_connection(fail_silently).send_messages([self])
  File "C:\Python\Python39\lib\site-packages\django\core\mail\backends\smtp.py", line 102, in send_messages
    new_conn_created = self.open()
  File "C:\Python\Python39\lib\site-packages\django\core\mail\backends\smtp.py", line 67, in open
    self.connection.starttls(keyfile=self.ssl_keyfile, certfile=self.ssl_certfile)
  File "C:\Python\Python39\lib\smtplib.py", line 764, in starttls
    self.ehlo_or_helo_if_needed()
  File "C:\Python\Python39\lib\smtplib.py", line 607, in ehlo_or_helo_if_needed
    (code, resp) = self.helo()
  File "C:\Python\Python39\lib\smtplib.py", line 436, in helo
    (code, msg) = self.getreply()
  File "C:\Python\Python39\lib\smtplib.py", line 400, in getreply
    raise SMTPServerDisconnected("Connection unexpectedly closed")

Exception Type: SMTPServerDisconnected at /contact-me/
Exception Value: Connection unexpectedly closed

排查与解决建议 #

• 检查网络拦截：本地测试时，确认防火墙、杀毒软件没有拦截587端口的出站请求；生产环境需确保服务器能访问smtp.gmail.com的587或465端口
• 重新生成应用专用密码：登录Gmail账户，进入「安全」-「应用专用密码」，重新生成一个密码（选择「邮件」类型），复制时不要带多余空格，替换到配置里
• 切换SMTP端口与加密方式：尝试改用SSL加密，修改配置：

  EMAIL_PORT = 465
  EMAIL_USE_SSL = True
  # 注释掉 EMAIL_USE_TLS = True
  

• 修正发件人地址：Gmail不允许用未验证的外部邮箱作为发件人，把EmailMessage的第三个参数改成自己的Gmail地址，同时避免变量名冲突：

  # 避免覆盖用户提交的email变量，改用email_msg作为实例名
  email_msg = EmailMessage(
      'New message from {} <{}>'.format(name, email),
      'From {} <{}>\n\nWrote:\n\n{}'.format(name, email, content),
      settings.EMAIL_HOST_USER,  # 改为自己的Gmail地址
      [settings.EMAIL_HOST_USER]
  )
  

• 查看Gmail安全日志：登录Gmail后，在「安全」页面查看最近的登录活动，确认是否有被标记为异常的登录尝试，若有则点击「这是我」解锁账户

内容的提问来源于stack exchange，提问作者GerRubio