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Python SMTP

category: 编程语言

Python SMTP 发送电子邮件完整指南

Python提供了多种方式来发送电子邮件，主要通过smtplib模块实现。以下是使用Python发送电子邮件的详细说明。

1. 基本配置

安装要求

Python内置smtplib和email模块，无需额外安装：

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

获取SMTP服务器信息

常见邮件服务SMTP设置：

服务商SMTP服务器端口加密方式
Gmailsmtp.gmail.com587TLS
Outlooksmtp.office365.com587STARTTLS
QQ邮箱smtp.qq.com465SSL
163邮箱smtp.163.com465SSL

2. 发送简单文本邮件

基本示例

def send_text_email():
    # 邮件内容配置
    sender = '[email protected]'
    receivers = ['[email protected]', '[email protected]']
    
    # 创建邮件对象
    message = MIMEText('这是邮件正文内容，纯文本格式', 'plain', 'utf-8')
    message['From'] = Header("发送者名称 <%s>" % sender, 'utf-8')
    message['To'] = Header("接收者名称", 'utf-8')
    message['Subject'] = Header('Python邮件测试', 'utf-8')
    
    try:
        # 连接SMTP服务器
        smtp_obj = smtplib.SMTP('smtp.example.com', 587)
        smtp_obj.starttls()  # 启用TLS加密
        smtp_obj.login('your_username', 'your_password')
        
        # 发送邮件
        smtp_obj.sendmail(sender, receivers, message.as_string())
        print("邮件发送成功")
        
    except smtplib.SMTPException as e:
        print(f"邮件发送失败: {e}")
    finally:
        smtp_obj.quit()

send_text_email()

3. 发送HTML格式邮件

HTML邮件示例

def send_html_email():
    sender = '[email protected]'
    receivers = ['[email protected]']
    
    # HTML内容
    html_content = """
    <html>
    <body>
        <h1 style="color: #446688;">Python邮件测试</h1>
        <p>这是一封<strong>HTML格式</strong>的测试邮件。</p>
        <p><a href="https://www.python.org">点击访问Python官网</a></p>
    </body>
    </html>
    """
    
    message = MIMEText(html_content, 'html', 'utf-8')
    message['From'] = sender
    message['To'] = ', '.join(receivers)
    message['Subject'] = 'HTML格式邮件测试'
    
    try:
        with smtplib.SMTP_SSL('smtp.example.com', 465) as smtp:
            smtp.login('your_username', 'your_password')
            smtp.sendmail(sender, receivers, message.as_string())
        print("HTML邮件发送成功")
    except Exception as e:
        print(f"发送失败: {e}")

send_html_email()

4. 发送带附件的邮件

附件邮件示例

from email.mime.application import MIMEApplication
from email.mime.base import MIMEBase
from email import encoders
import os

def send_attachment_email():
    sender = '[email protected]'
    receivers = ['[email protected]']
    
    # 创建多部分消息对象
    message = MIMEMultipart()
    message['From'] = sender
    message['To'] = ', '.join(receivers)
    message['Subject'] = '带附件的测试邮件'
    
    # 邮件正文
    message.attach(MIMEText('这是一封带有附件的测试邮件', 'plain', 'utf-8'))
    
    # 添加附件1：直接附加文件
    file_path = 'example.pdf'
    with open(file_path, 'rb') as f:
        attach = MIMEApplication(f.read(), _subtype="pdf")
        attach.add_header('Content-Disposition', 'attachment', filename=os.path.basename(file_path))
        message.attach(attach)
    
    # 添加附件2：使用MIMEBase
    file_path = 'data.xlsx'
    with open(file_path, 'rb') as f:
        part = MIMEBase('application', 'octet-stream')
        part.set_payload(f.read())
        encoders.encode_base64(part)
        part.add_header('Content-Disposition', f'attachment; filename="{os.path.basename(file_path)}"')
        message.attach(part)
    
    try:
        with smtplib.SMTP('smtp.office365.com', 587) as smtp:
            smtp.starttls()
            smtp.login('your_username', 'your_password')
            smtp.sendmail(sender, receivers, message.as_string())
        print("带附件邮件发送成功")
    except Exception as e:
        print(f"发送失败: {e}")

send_attachment_email()

5. 发送带图片的HTML邮件

内嵌图片邮件

from email.mime.image import MIMEImage

def send_html_with_image():
    sender = '[email protected]'
    receivers = ['[email protected]']
    
    # 创建多部分消息(related类型允许内嵌资源)
    msg_root = MIMEMultipart('related')
    msg_root['From'] = sender
    msg_root['To'] = ', '.join(receivers)
    msg_root['Subject'] = '带图片的HTML邮件'
    
    # 创建替代部分(同时支持纯文本和HTML)
    msg_alternative = MIMEMultipart('alternative')
    msg_root.attach(msg_alternative)
    
    # 纯文本部分
    msg_alternative.attach(MIMEText('您的邮件客户端不支持HTML显示', 'plain', 'utf-8'))
    
    # HTML部分(引用图片cid)
    html_content = """
    <html>
    <body>
        <h1>带图片的邮件</h1>
        <p>这是一封包含内嵌图片的HTML邮件</p>
        <p><img src="cid:image1" width="300"></p>
    </body>
    </html>
    """
    msg_alternative.attach(MIMEText(html_content, 'html', 'utf-8'))
    
    # 添加图片
    image_path = 'example.jpg'
    with open(image_path, 'rb') as f:
        msg_image = MIMEImage(f.read())
        msg_image.add_header('Content-ID', '<image1>')
        msg_root.attach(msg_image)
    
    try:
        with smtplib.SMTP_SSL('smtp.qq.com', 465) as smtp:
            smtp.login('your_username', 'your_password')
            smtp.sendmail(sender, receivers, msg_root.as_string())
        print("带图片的HTML邮件发送成功")
    except Exception as e:
        print(f"发送失败: {e}")

send_html_with_image()

6. 使用Gmail发送邮件

Gmail特殊配置

def send_via_gmail():
    sender = '[email protected]'
    password = 'your_app_password'  # 建议使用应用专用密码
    receivers = ['[email protected]']
    
    message = MIMEMultipart()
    message['From'] = sender
    message['To'] = ', '.join(receivers)
    message['Subject'] = '通过Gmail发送的测试邮件'
    
    message.attach(MIMEText('这是通过Gmail SMTP服务器发送的邮件', 'plain'))
    
    try:
        # Gmail需要更安全的连接
        with smtplib.SMTP_SSL('smtp.gmail.com', 465) as smtp:
            smtp.login(sender, password)
            smtp.sendmail(sender, receivers, message.as_string())
        print("通过Gmail发送邮件成功")
    except Exception as e:
        print(f"发送失败: {e}")
        # 如果启用了两步验证，需要创建应用专用密码
        # 或者尝试降低安全性: https://myaccount.google.com/lesssecureapps

send_via_gmail()

7. 批量发送邮件

批量发送示例

import csv

def batch_send_emails():
    sender = '[email protected]'
    password = 'your_password'
    
    # 从CSV读取收件人列表
    with open('recipients.csv', mode='r', encoding='utf-8') as f:
        reader = csv.DictReader(f)
        recipients = [row for row in reader]
    
    # 连接SMTP服务器(只连接一次)
    with smtplib.SMTP('smtp.example.com', 587) as smtp:
        smtp.starttls()
        smtp.login(sender, password)
        
        for recipient in recipients:
            # 为每个收件人创建个性化邮件
            message = MIMEMultipart()
            message['From'] = sender
            message['To'] = recipient['email']
            message['Subject'] = f"亲爱的{recipient['name']}, 这是给您的专属邮件"
            
            # 个性化内容
            body = f"""
            尊敬的{recipient['name']}:
            
            感谢您对我们的关注，根据我们的记录，您来自{recipient['city']}。
            这是一封个性化邮件。
            """
            message.attach(MIMEText(body, 'plain', 'utf-8'))
            
            try:
                smtp.sendmail(sender, [recipient['email']], message.as_string())
                print(f"发送给 {recipient['email']} 成功")
            except Exception as e:
                print(f"发送给 {recipient['email']} 失败: {e}")

batch_send_emails()

8. 邮件发送最佳实践

1. 安全性建议

  • 不要将密码硬编码在代码中，使用环境变量或配置文件
  • 考虑使用OAuth2认证代替明文密码
  • 为应用创建专用邮箱账户

2. 性能优化

  • 批量发送时复用SMTP连接
  • 使用多线程发送大量邮件
  • 考虑使用邮件发送服务(SendGrid, Mailgun等)

3. 避免被标记为垃圾邮件

  • 设置合理的From头
  • 包含退订链接
  • 平衡文本和图片比例
  • 避免使用垃圾邮件常用关键词

9. 高级主题

使用OAuth2认证(Gmail)

import os
import smtplib
import base64
from email.message import EmailMessage
from google.oauth2.credentials import Credentials
from google_auth_oauthlib.flow import InstalledAppFlow

def send_with_oauth2():
    # 配置OAuth2
    SCOPES = ['https://mail.google.com/']
    creds = None
    
    if os.path.exists('token.json'):
        creds = Credentials.from_authorized_user_file('token.json', SCOPES)
    
    if not creds or not creds.valid:
        flow = InstalledAppFlow.from_client_secrets_file('credentials.json', SCOPES)
        creds = flow.run_local_server(port=0)
        with open('token.json', 'w') as token:
            token.write(creds.to_json())
    
    # 创建邮件
    message = EmailMessage()
    message['From'] = '[email protected]'
    message['To'] = '[email protected]'
    message['Subject'] = '使用OAuth2发送的邮件'
    message.set_content('这是通过OAuth2认证发送的邮件')
    
    try:
        with smtplib.SMTP_SSL('smtp.gmail.com', 465) as smtp:
            smtp.ehlo()
            auth_string = f"user={message['From']}\1auth=Bearer {creds.token}\1\1"
            smtp.docmd('AUTH', 'XOAUTH2 ' + base64.b64encode(auth_string.encode()).decode())
            smtp.send_message(message)
        print("邮件发送成功")
    except Exception as e:
        print(f"发送失败: {e}")

send_with_oauth2()

异步发送邮件

import asyncio
import aiosmtplib

async def async_send_email():
    message = aiosmtplib.email.message.EmailMessage()
    message["From"] = "[email protected]"
    message["To"] = "[email protected]"
    message["Subject"] = "异步发送的邮件"
    message.set_content("这是通过aiosmtplib异步发送的邮件")
    
    try:
        await aiosmtplib.send(
            message,
            hostname="smtp.example.com",
            port=587,
            username="your_username",
            password="your_password",
            start_tls=True
        )
        print("异步邮件发送成功")
    except Exception as e:
        print(f"发送失败: {e}")

asyncio.run(async_send_email())

10. 常见问题解决

1. 认证失败

# 错误: smtplib.SMTPAuthenticationError
# 解决方案:
# - 检查用户名密码是否正确
# - Gmail可能需要启用"不太安全的应用": https://myaccount.google.com/lesssecureapps
# - 或者使用应用专用密码

2. 连接超时

# 错误: socket.timeout 或 smtplib.SMTPServerDisconnected
# 解决方案:
# - 检查SMTP服务器地址和端口是否正确
# - 尝试使用SMTP_SSL或调整超时时间
smtp = smtplib.SMTP('smtp.example.com', 587, timeout=10)

3. 附件编码问题

# 错误: UnicodeEncodeError
# 解决方案:
# - 确保文件名正确编码
filename = Header('中文文件.txt', 'utf-8').encode()
part.add_header('Content-Disposition', 'attachment', filename=filename)

11. 实际应用示例

邮件通知系统

import smtplib
from email.mime.text import MIMEText
from datetime import datetime

class EmailNotifier:
    def __init__(self, smtp_server, port, username, password, use_ssl=False):
        self.smtp_server = smtp_server
        self.port = port
        self.username = username
        self.password = password
        self.use_ssl = use_ssl
    
    def send_notification(self, to_email, subject, content):
        message = MIMEText(content, 'plain', 'utf-8')
        message['From'] = self.username
        message['To'] = to_email
        message['Subject'] = subject
        
        try:
            if self.use_ssl:
                with smtplib.SMTP_SSL(self.smtp_server, self.port) as smtp:
                    smtp.login(self.username, self.password)
                    smtp.sendmail(self.username, [to_email], message.as_string())
            else:
                with smtplib.SMTP(self.smtp_server, self.port) as smtp:
                    smtp.starttls()
                    smtp.login(self.username, self.password)
                    smtp.sendmail(self.username, [to_email], message.as_string())
            return True
        except Exception as e:
            print(f"发送通知到 {to_email} 失败: {e}")
            return False

# 使用示例
notifier = EmailNotifier(
    smtp_server='smtp.example.com',
    port=587,
    username='[email protected]',
    password='password'
)

# 发送系统警报
alert_time = datetime.now().strftime('%Y-%m-%d %H:%M:%S')
notifier.send_notification(
    to_email='[email protected]',
    subject=f'系统警报 - {alert_time}',
    content='磁盘空间使用超过90%，请及时处理！'
)

12. 总结

Python发送邮件的主要方法：

需求使用模块/技术
基本文本邮件smtplib + MIMEText
HTML邮件MIMEText设置html子类型
带附件邮件MIMEMultipart + MIMEApplication
内嵌图片邮件MIMEMultipart('related') + MIMEImage
批量发送CSV读取 + SMTP连接复用
高级认证OAuth2
异步发送aiosmtplib

掌握这些技术可以满足从简单通知到复杂邮件的各种发送需求。对于生产环境，建议考虑专业的邮件发送服务如SendGrid或Mailgun，它们提供更可靠的投递率和更丰富的API功能。