smtplib发送邮件超时错误求助：已排查配置仍无法成功发送

问题重现 #

运行以下代码时出现TimeoutError: [WinError 10060] A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond：

import smtplib

myemail = "sender@gmail.com"
password_code = "ieruweioruiweoru"
with smtplib.SMTP("smtp.gmail.com") as connection:
    connection.starttls()
    connection.login(user=myemail, password=password_code)
    connection.sendmail(from_addr=myemail, to_addrs="reciever@gmail.com", msg="this is body")

解决方案 #

• 指定正确的SMTP端口：Gmail SMTP默认端口为587，未显式指定端口是常见的连接失败原因，同时sendmail的msg参数需符合邮件格式规范（包含必要头信息），修改代码如下：

  import smtplib
  
  myemail = "sender@gmail.com"
  password_code = "ieruweioruiweoru"
  # 显式指定587端口
  with smtplib.SMTP("smtp.gmail.com", 587) as connection:
      connection.starttls()
      connection.login(user=myemail, password=password_code)
      # 补充邮件头，避免被识别为垃圾邮件
      msg = f"From: {myemail}\nTo: reciever@gmail.com\nSubject: Test Email\n\nthis is body"
      connection.sendmail(from_addr=myemail, to_addrs="reciever@gmail.com", msg=msg)
  

• 检查网络与防火墙拦截：

  • 临时关闭本地防火墙、杀毒软件，测试是否能正常连接；
  • 用命令行验证端口连通性：执行telnet smtp.gmail.com 587，若返回220 smtp.gmail.com ESMTP则端口正常，否则说明端口被拦截。

• 确认Gmail认证权限：

  • 若账号开启了两步验证，必须使用谷歌账号「安全」设置中生成的应用密码（App Password）代替原密码；
  • 未开启两步验证的账号，需确保谷歌账号允许“不太安全的应用访问”（注：谷歌已逐步移除该选项，优先推荐使用应用密码）。

• 改用SMTP_SSL连接：若starttls方式仍有问题，尝试直接使用SSL加密连接465端口：

  import smtplib
  
  myemail = "sender@gmail.com"
  password_code = "ieruweioruiweoru"
  with smtplib.SMTP_SSL("smtp.gmail.com", 465) as connection:
      connection.login(user=myemail, password=password_code)
      msg = f"From: {myemail}\nTo: reciever@gmail.com\nSubject: Test Email\n\nthis is body"
      connection.sendmail(from_addr=myemail, to_addrs="reciever@gmail.com", msg=msg)
  

• 排查DNS解析问题：若本地无法解析smtp.gmail.com，可切换DNS服务器为谷歌公共DNS（8.8.8.8）后重试。

内容的提问来源于stack exchange，提问作者techno adnan