Python通过代理服务器连接O365时出现HTTPS连接失败问题

问题现象 #

本地运行正常的O365邮件读写代码，部署到需代理访问外网的服务器时，出现连接超时错误：

urllib3.exceptions.MaxRetryError: HTTPSConnectionPool(host='login.microsoftonline.com', port=443): Max retries exceeded with url: /2d11ad74-bbf6-403f-32c7-6ff0e039a923/oauth2/v2.0/token (Caused by NewConnectionError('<urllib3.connection.HTTPSConnection object at 0x000002507067C348>: Failed to establish a new connection: [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'))

原代码如下：

import settings
from exchangelib import Credentials, Account, DELEGATE, BASIC, \
    Configuration, NTLM, Message, Mailbox, FileAttachment, HTMLBody, FaultTolerance, IMPERSONATION
from exchangelib.protocol import BaseProtocol, NoVerifyHTTPAdapter
from exchangelib import OAuth2LegacyCredentials

credentials = OAuth2LegacyCredentials(
  client_id= settings.clientId, client_secret= settings.clientSecret,
  tenant_id=settings.tenentId,
  username=settings.eUserName, password=settings.ePassword
)
config = Configuration(server = 'smtp.office365.com', credentials=credentials)
account = Account(settings.eUserName, config=config, access_type=DELEGATE)

m = Message(
  account=account,
  subject='Any Subject OAth2 Authentication',
  body=HTMLBody('OAth2 Authentication'),
  to_recipients=map(lambda x: Mailbox(email_address=x), ['myEmail@gmail.com'])
)

for item in account.inbox.all()[:10]:
  print (item.sender.email_address)

m.send()
print('Email is being sent...')

问题原因 #

代码未配置代理服务器信息，导致无法通过代理连接微软OAuth2认证服务器（login.microsoftonline.com），进而无法获取访问令牌，最终触发连接超时。

解决方案 #

exchangelib基于requests库实现网络请求，只需为其协议层配置代理即可。具体步骤如下：

• 配置代理地址、端口（若需认证需额外添加用户名和密码）
• 为BaseProtocol挂载带代理的HTTP适配器

修改后的完整代码：

import settings
from exchangelib import Credentials, Account, DELEGATE, \
    Configuration, Message, Mailbox, HTMLBody
from exchangelib.protocol import BaseProtocol, NoVerifyHTTPAdapter
from exchangelib import OAuth2LegacyCredentials
import requests

# 配置代理信息，替换为实际代理地址和端口
PROXY_URL = "http://your-proxy-server:port"
# 若代理需认证，使用格式："http://username:password@your-proxy-server:port"

# 创建带代理的会话
session = requests.Session()
session.proxies = {
    "http": PROXY_URL,
    "https": PROXY_URL,
}
# 挂载适配器到exchangelib协议层
BaseProtocol.HTTP_ADAPTER_CLS = NoVerifyHTTPAdapter
BaseProtocol.session = session

credentials = OAuth2LegacyCredentials(
    client_id=settings.clientId,
    client_secret=settings.clientSecret,
    tenant_id=settings.tenentId,
    username=settings.eUserName,
    password=settings.ePassword
)
# 修正服务器地址：exchangelib使用EWS协议，需指向outlook.office365.com
config = Configuration(server='outlook.office365.com', credentials=credentials)
account = Account(settings.eUserName, config=config, access_type=DELEGATE)

m = Message(
    account=account,
    subject='OAuth2 Authentication 测试邮件',
    body=HTMLBody('这是OAuth2认证的测试邮件'),
    to_recipients=[Mailbox(email_address='myEmail@gmail.com')]
)

# 读取收件箱前10封邮件
for item in account.inbox.all()[:10]:
    print(item.sender.email_address)

m.send()
print('邮件已发送...')

额外注意事项 #

• 确保代理服务器支持HTTPS请求，地址、端口配置准确
• 若代理需要身份认证，在PROXY_URL中按格式加入用户名和密码
• 原代码中server配置为smtp.office365.com错误，exchangelib依赖EWS协议，必须使用outlook.office365.com

内容的提问来源于stack exchange，提问作者M. Antoney