SMTP（Simple Mail Transfer Protocol）是用于发送电子邮件的协议。Python 的 smtplib 模块提供了发送邮件的功能，email 模块用于构建邮件内容。

安装与基本导入

SMTP 模块是 Python 标准库的一部分，无需额外安装：

import smtplib
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from email.mime.application import MIMEApplication
from email.header import Header
from email.utils import formataddr
import os

基本邮件发送

1. 发送纯文本邮件

def send_simple_email():
    # 邮件服务器配置
    smtp_server = "smtp.163.com"  # 以163邮箱为例
    smtp_port = 25                # 端口：25(普通), 465(SSL), 587(TLS)
    sender_email = "your_email@163.com"
    password = "your_password"    # 如果是163邮箱，使用授权码而非登录密码
    
    # 收件人
    receiver_email = "receiver@example.com"
    
    # 创建邮件内容
    subject = "测试邮件主题"
    body = "这是一封测试邮件的正文内容。"
    
    # 构建邮件
    message = MIMEText(body, 'plain', 'utf-8')
    message['From'] = formataddr(("发件人名称", sender_email))
    message['To'] = formataddr(("收件人名称", receiver_email))
    message['Subject'] = Header(subject, 'utf-8')
    
    try:
        # 连接服务器并发送
        with smtplib.SMTP(smtp_server, smtp_port) as server:
            server.login(sender_email, password)
            server.sendmail(sender_email, receiver_email, message.as_string())
        print("邮件发送成功！")
    except Exception as e:
        print(f"邮件发送失败: {e}")

# send_simple_email()

2. 不同加密方式连接

def connect_with_different_encryption():
    smtp_server = "smtp.163.com"
    sender_email = "your_email@163.com"
    password = "your_password"
    
    # 方式1: 普通连接（不推荐，可能被拦截）
    try:
        server = smtplib.SMTP(smtp_server, 25)
        server.login(sender_email, password)
        print("普通连接成功")
        server.quit()
    except Exception as e:
        print(f"普通连接失败: {e}")
    
    # 方式2: SSL加密连接
    try:
        server = smtplib.SMTP_SSL(smtp_server, 465)
        server.login(sender_email, password)
        print("SSL连接成功")
        server.quit()
    except Exception as e:
        print(f"SSL连接失败: {e}")
    
    # 方式3: STARTTLS加密连接
    try:
        server = smtplib.SMTP(smtp_server, 587)
        server.starttls()  # 启用加密
        server.login(sender_email, password)
        print("STARTTLS连接成功")
        server.quit()
    except Exception as e:
        print(f"STARTTLS连接失败: {e}")

复杂邮件发送

1. 发送HTML格式邮件

def send_html_email():
    smtp_server = "smtp.163.com"
    smtp_port = 465
    sender_email = "your_email@163.com"
    password = "your_password"
    receiver_email = "receiver@example.com"
    
    # HTML内容
    subject = "HTML格式测试邮件"
    html_body = """
    <html>
        <body>
            <h1 style="color: #ff6600;">这是一封HTML邮件</h1>
            <p>欢迎使用<strong>Python SMTP</strong>模块发送邮件！</p>
            <ul>
                <li>列表项1</li>
                <li>列表项2</li>
                <li>列表项3</li>
            </ul>
            <p><a href="https://www.python.org">访问Python官网</a></p>
        </body>
    </html>
    """
    
    # 创建HTML邮件
    message = MIMEText(html_body, 'html', 'utf-8')
    message['From'] = formataddr(("发件人", sender_email))
    message['To'] = formataddr(("收件人", receiver_email))
    message['Subject'] = Header(subject, 'utf-8')
    
    try:
        with smtplib.SMTP_SSL(smtp_server, smtp_port) as server:
            server.login(sender_email, password)
            server.sendmail(sender_email, receiver_email, message.as_string())
        print("HTML邮件发送成功！")
    except Exception as e:
        print(f"HTML邮件发送失败: {e}")

2. 发送带附件的邮件

def send_email_with_attachment():
    smtp_server = "smtp.163.com"
    smtp_port = 465
    sender_email = "your_email@163.com"
    password = "your_password"
    receiver_email = "receiver@example.com"
    
    # 创建多部分邮件
    message = MIMEMultipart()
    message['From'] = formataddr(("发件人", sender_email))
    message['To'] = formataddr(("收件人", receiver_email))
    message['Subject'] = Header("带附件的测试邮件", 'utf-8')
    
    # 邮件正文
    text_body = """
    您好！
    
    这是一封带有附件的测试邮件。
    请查收附件中的文件。
    
    祝好！
    Python发件程序
    """
    
    # 添加文本部分
    text_part = MIMEText(text_body, 'plain', 'utf-8')
    message.attach(text_part)
    
    # 添加附件1：文本文件
    attachment1 = MIMEApplication(open('example.txt', 'rb').read())
    attachment1.add_header('Content-Disposition', 'attachment', 
                          filename=Header('示例文件.txt', 'utf-8').encode())
    message.attach(attachment1)
    
    # 添加附件2：图片文件
    try:
        with open('image.jpg', 'rb') as f:
            attachment2 = MIMEApplication(f.read())
            attachment2.add_header('Content-Disposition', 'attachment',
                                 filename=Header('图片.jpg', 'utf-8').encode())
            message.attach(attachment2)
    except FileNotFoundError:
        print("图片文件未找到，跳过添加图片附件")
    
    try:
        with smtplib.SMTP_SSL(smtp_server, smtp_port) as server:
            server.login(sender_email, password)
            server.sendmail(sender_email, receiver_email, message.as_string())
        print("带附件的邮件发送成功！")
    except Exception as e:
        print(f"邮件发送失败: {e}")

3. 发送混合内容邮件（文本+HTML）

def send_mixed_email():
    smtp_server = "smtp.163.com"
    smtp_port = 465
    sender_email = "your_email@163.com"
    password = "your_password"
    receiver_email = "receiver@example.com"
    
    # 创建多部分邮件（alternative类型）
    message = MIMEMultipart('alternative')
    message['From'] = formataddr(("发件人", sender_email))
    message['To'] = formataddr(("收件人", receiver_email))
    message['Subject'] = Header("混合内容测试邮件", 'utf-8')
    
    # 纯文本版本（用于不支持HTML的邮件客户端）
    text_body = """
    这是一封测试邮件。
    如果您看到这条消息，说明您的邮件客户端不支持HTML格式。
    请使用支持HTML的邮件客户端查看完整内容。
    """
    
    # HTML版本
    html_body = """
    <html>
        <body>
            <h1 style="color: #3366cc;">欢迎！</h1>
            <p>这是一封<strong>HTML格式</strong>的测试邮件。</p>
            <p>如果您的邮件客户端支持HTML，您将看到格式化的内容。</p>
            <table border="1" style="border-collapse: collapse;">
                <tr>
                    <th>项目</th>
                    <th>值</th>
                </tr>
                <tr>
                    <td>名称</td>
                    <td>测试数据</td>
                </tr>
            </table>
        </body>
    </html>
    """
    
    # 添加两个版本（邮件客户端会选择支持的格式）
    text_part = MIMEText(text_body, 'plain', 'utf-8')
    html_part = MIMEText(html_body, 'html', 'utf-8')
    
    message.attach(text_part)
    message.attach(html_part)
    
    try:
        with smtplib.SMTP_SSL(smtp_server, smtp_port) as server:
            server.login(sender_email, password)
            server.sendmail(sender_email, receiver_email, message.as_string())
        print("混合内容邮件发送成功！")
    except Exception as e:
        print(f"邮件发送失败: {e}")

高级功能

1. 批量发送邮件

def send_batch_emails():
    smtp_server = "smtp.163.com"
    smtp_port = 465
    sender_email = "your_email@163.com"
    password = "your_password"
    
    # 收件人列表
    receivers = [
        {"name": "张三", "email": "zhangsan@example.com"},
        {"name": "李四", "email": "lisi@example.com"},
        {"name": "王五", "email": "wangwu@example.com"}
    ]
    
    try:
        with smtplib.SMTP_SSL(smtp_server, smtp_port) as server:
            server.login(sender_email, password)
            
            for receiver in receivers:
                # 为每个收件人个性化邮件
                subject = f"亲爱的{receiver['name']}，这是一封个性化邮件"
                body = f"""
                尊敬的{receiver['name']}：
                
                这是一封个性化测试邮件。
                感谢您使用我们的服务！
                
                祝好！
                Python发件系统
                """
                
                message = MIMEText(body, 'plain', 'utf-8')
                message['From'] = formataddr(("系统发件人", sender_email))
                message['To'] = formataddr((receiver['name'], receiver['email']))
                message['Subject'] = Header(subject, 'utf-8')
                
                server.sendmail(sender_email, receiver['email'], message.as_string())
                print(f"发送给 {receiver['name']} 的邮件成功！")
                
                # 避免发送过快被服务器限制
                import time
                time.sleep(1)
                
    except Exception as e:
        print(f"批量发送失败: {e}")

2. 邮件发送类封装

class EmailSender:
    def __init__(self, smtp_server, smtp_port, sender_email, password, use_ssl=True):
        self.smtp_server = smtp_server
        self.smtp_port = smtp_port
        self.sender_email = sender_email
        self.password = password
        self.use_ssl = use_ssl
        
    def connect(self):
        """连接邮件服务器"""
        try:
            if self.use_ssl:
                self.server = smtplib.SMTP_SSL(self.smtp_server, self.smtp_port)
            else:
                self.server = smtplib.SMTP(self.smtp_server, self.smtp_port)
                self.server.starttls()  # 启用TLS加密
            
            self.server.login(self.sender_email, self.password)
            return True
        except Exception as e:
            print(f"连接失败: {e}")
            return False
    
    def send_email(self, to_email, to_name, subject, body, 
                  html_body=None, attachments=None):
        """发送邮件"""
        try:
            # 创建邮件
            if html_body or attachments:
                message = MIMEMultipart()
                if html_body:
                    message = MIMEMultipart('alternative')
            else:
                message = MIMEText(body, 'plain', 'utf-8')
            
            message['From'] = formataddr(("系统发件人", self.sender_email))
            message['To'] = formataddr((to_name, to_email))
            message['Subject'] = Header(subject, 'utf-8')
            
            # 添加正文
            if html_body:
                text_part = MIMEText(body, 'plain', 'utf-8')
                html_part = MIMEText(html_body, 'html', 'utf-8')
                message.attach(text_part)
                message.attach(html_part)
            elif attachments:
                text_part = MIMEText(body, 'plain', 'utf-8')
                message.attach(text_part)
            
            # 添加附件
            if attachments:
                for attachment_path in attachments:
                    if os.path.exists(attachment_path):
                        with open(attachment_path, 'rb') as f:
                            attachment = MIMEApplication(f.read())
                            filename = os.path.basename(attachment_path)
                            attachment.add_header('Content-Disposition', 'attachment',
                                                filename=Header(filename, 'utf-8').encode())
                            message.attach(attachment)
            
            # 发送邮件
            self.server.sendmail(self.sender_email, to_email, message.as_string())
            return True
            
        except Exception as e:
            print(f"发送失败: {e}")
            return False
    
    def disconnect(self):
        """断开连接"""
        if hasattr(self, 'server'):
            self.server.quit()

# 使用示例
def use_email_sender():
    # 创建发送器实例
    sender = EmailSender(
        smtp_server="smtp.163.com",
        smtp_port=465,
        sender_email="your_email@163.com",
        password="your_password",
        use_ssl=True
    )
    
    # 连接服务器
    if sender.connect():
        # 发送简单邮件
        sender.send_email(
            to_email="receiver@example.com",
            to_name="收件人",
            subject="测试邮件",
            body="这是一封测试邮件。"
        )
        
        # 发送带HTML的邮件
        sender.send_email(
            to_email="receiver@example.com",
            to_name="收件人",
            subject="HTML测试邮件",
            body="纯文本内容",
            html_body="<h1>HTML内容</h1><p>这是HTML版本</p>"
        )
        
        # 断开连接
        sender.disconnect()

3. 常见邮箱服务器配置

# 常见邮箱服务器配置
EMAIL_CONFIGS = {
    '163': {
        'smtp_server': 'smtp.163.com',
        'smtp_port': 465,
        'use_ssl': True
    },
    'qq': {
        'smtp_server': 'smtp.qq.com',
        'smtp_port': 465,
        'use_ssl': True
    },
    'gmail': {
        'smtp_server': 'smtp.gmail.com',
        'smtp_port': 587,  # Gmail 使用 STARTTLS
        'use_ssl': False
    },
    'outlook': {
        'smtp_server': 'smtp.office365.com',
        'smtp_port': 587,
        'use_ssl': False
    }
}

def get_email_config(email_address):
    """根据邮箱地址获取配置"""
    if '@163.com' in email_address:
        return EMAIL_CONFIGS['163']
    elif '@qq.com' in email_address:
        return EMAIL_CONFIGS['qq']
    elif '@gmail.com' in email_address:
        return EMAIL_CONFIGS['gmail']
    elif '@outlook.com' in email_address or '@hotmail.com' in email_address:
        return EMAIL_CONFIGS['outlook']
    else:
        raise ValueError("不支持的邮箱类型")

错误处理与调试

def robust_email_sending():
    smtp_server = "smtp.163.com"
    sender_email = "your_email@163.com"
    password = "your_password"
    
    try:
        # 测试连接
        server = smtplib.SMTP_SSL(smtp_server, 465)
        server.set_debuglevel(1)  # 开启调试模式，显示通信详情
        
        # 登录
        server.login(sender_email, password)
        print("登录成功")
        
        # 发送测试邮件
        message = MIMEText("测试邮件内容", 'plain', 'utf-8')
        message['From'] = sender_email
        message['To'] = "receiver@example.com"
        message['Subject'] = "测试邮件"
        
        server.sendmail(sender_email, "receiver@example.com", message.as_string())
        print("邮件发送成功")
        
        server.quit()
        
    except smtplib.SMTPAuthenticationError:
        print("认证失败：用户名或密码错误")
    except smtplib.SMTPConnectError:
        print("连接服务器失败")
    except smtplib.SMTPRecipientsRefused:
        print("收件人被拒绝")
    except smtplib.SMTPSenderRefused:
        print("发件人被拒绝")
    except smtplib.SMTPDataError:
        print("服务器拒绝数据")
    except Exception as e:
        print(f"其他错误: {e}")

安全注意事项

import getpass
from configparser import ConfigParser

def secure_email_sending():
    # 安全地获取密码（不显示在终端）
    password = getpass.getpass("请输入邮箱密码/授权码: ")
    
    # 或者从配置文件读取（推荐）
    config = ConfigParser()
    config.read('email_config.ini')
    
    smtp_server = config.get('email', 'smtp_server')
    sender_email = config.get('email', 'sender_email')
    password = config.get('email', 'password')  # 加密存储
    
    # 使用环境变量（更安全）
    import os
    password = os.getenv('EMAIL_PASSWORD')
    
    # 发送邮件...

总结

主要优点：

  • Python 标准库，无需额外安装
  • 支持多种邮件格式（文本、HTML、附件等）
  • 支持多种加密方式（SSL/TLS）
  • 灵活的邮件构建功能

常见问题解决：

  1. 认证失败：检查是否使用授权码而非登录密码
  2. 连接超时：检查网络连接和防火墙设置
  3. 被拒收：检查发件人信誉和邮件内容是否被标记为垃圾邮件

最佳实践：

  • 使用加密连接（SSL/TLS）
  • 密码/授权码安全存储
  • 添加适当的错误处理
  • 避免发送垃圾邮件
  • 测试不同的邮件客户端兼容性

SMTP 模块是 Python 发送邮件的标准解决方案，适用于各种邮件发送需求。