使用Python通过Outlook发送邮件时偶发SMTPDataError问题求助

我用Python脚本通过Outlook发送邮件时，偶尔会触发以下错误，但有时候邮件又能正常发送：

Traceback (most recent call last):
  File "c:\Users\Variable\Documents\python_files\learning_new\sending_email.py", line 23, in <module>
    session.sendmail(sender_address, receiver_address, text)
  File "C:\Users\Variable\AppData\Local\Programs\Python\Python310\lib\smtplib.py", line 908, in sendmail
    raise SMTPDataError(code, resp)
smtplib.SMTPDataError: (554, b'5.2.0 STOREDRV.Submission.Exception:OutboundSpamException; Failed to process message due to a permanent exception with message [BeginDiagnosticData]WASCL UserAction verdict is not None. Actual verdict is Suspend, ShowTierUpgrade. OutboundSpamException: WASCL UserAction verdict is not None. Actual verdict is Suspend, ShowTierUpgrade.[EndDiagnosticData] [Hostname=PAXP193MB1710.EURP193.PROD.OUTLOOK.COM]')

我的Python代码如下：

import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText

mail_content = '''Hello,
This is a simple mail. There is only text, no attachments are there The mail is sent using 
Python SMTP library.
Thank You'''

# 邮件地址和密码
sender_address = 'Fahe_em@outlook.com'
sender_pass = '*********'
receiver_address = 'fah909190@gmail.com'

# 配置MIME
message = MIMEMultipart()
message['From'] = sender_address
message['To'] = receiver_address
message['Subject'] = 'A test mail sent by Python. It has an attachment.'   # 邮件主题

# 添加邮件正文
message.attach(MIMEText(mail_content, 'plain'))

# 创建SMTP会话
session = smtplib.SMTP('smtp.office365.com', 587)
session.starttls()  # 启用安全连接
session.login(sender_address, sender_pass)  # 登录账号
text = message.as_string()
session.sendmail(sender_address, receiver_address, text)
session.quit()
print('Mail Sent')   

问题原因分析 #

这个错误是Outlook反垃圾邮件机制触发的：

• OutboundSpamException 说明邮件被判定为疑似垃圾邮件，触发了临时发送限制
• 间歇性出现是因为反垃圾系统的判定并非固定规则，会受发送频率、邮件内容一致性、接收方反馈等因素影响

解决办法 #

1. 修正邮件内容矛盾点

   • 你的邮件主题写了"It has an attachment"，但正文明确说没有附件，这种矛盾描述会直接触发垃圾邮件判定，把主题改成贴合实际的内容，比如"Python测试邮件：纯文本无附件"
   • 清理正文中冗余或易触发判定的表述，保持内容逻辑一致

2. 控制发送频率与内容多样性

   • 不要短时间内重复发送完全相同的邮件，可以在正文末尾添加随机内容（比如当前时间戳）
   • 测试发送时，两次发送间隔至少1-2分钟，避免被判定为批量垃圾发送

3. 检查Outlook账号状态

   • 登录Outlook网页版，查看账号是否有发送限制提示，完成账号安全验证（比如二次验证）
   • 确认账号没有被标记为可疑发送者

4. 改用Microsoft Graph API发送
   SMTP方式容易触发反垃圾机制，官方Graph API的发送逻辑更贴合Outlook的规则，稳定性更高，示例代码框架如下：

   import requests
   
   # 需先通过Azure应用注册获取access token
   access_token = "你的access token"
   endpoint = "https://graph.microsoft.com/v1.0/me/sendMail"
   
   email_data = {
       "message": {
           "subject": "Python测试邮件",
           "body": {
               "contentType": "Text",
               "content": "这是通过Microsoft Graph API发送的测试邮件"
           },
           "toRecipients": [
               {
                   "emailAddress": {
                       "address": "fah909190@gmail.com"
                   }
               }
           ]
       },
       "saveToSentItems": "true"
   }
   
   response = requests.post(
       endpoint,
       headers={"Authorization": f"Bearer {access_token}", "Content-Type": "application/json"},
       json=email_data
   )
   
   if response.status_code == 202:
       print("邮件发送成功")
   else:
       print(f"发送失败: {response.text}")
   

内容的提问来源于stack exchange，提问作者Faheem