发送带附件的电子邮件

发送带附件的电子邮件技术详解

基础概念

发送带附件的电子邮件是通过SMTP协议在电子邮件中附加二进制或文本文件的过程。附件可以是文档、图片、音频、视频等各种类型的文件，它们会被编码后嵌入到电子邮件中。

实现方式

1. 使用编程语言发送

Python示例

import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from email.mime.base import MIMEBase
from email import encoders

def send_email_with_attachment(sender, receiver, subject, body, attachment_path):
    # 创建多部分消息对象
    message = MIMEMultipart()
    message['From'] = sender
    message['To'] = receiver
    message['Subject'] = subject
    
    # 添加邮件正文
    message.attach(MIMEText(body, 'plain'))
    
    # 打开附件文件
    with open(attachment_path, 'rb') as attachment:
        part = MIMEBase('application', 'octet-stream')
        part.set_payload(attachment.read())
    
    # 编码附件
    encoders.encode_base64(part)
    
    # 添加附件头
    part.add_header(
        'Content-Disposition',
        f'attachment; filename= {attachment_path.split("/")[-1]}'
    )
    
    # 将附件添加到消息中
    message.attach(part)
    
    # 发送邮件
    with smtplib.SMTP('smtp.example.com', 587) as server:
        server.starttls()
        server.login(sender, 'your_password')
        server.send_message(message)

# 使用示例
send_email_with_attachment(
    'sender@example.com',
    'receiver@example.com',
    '测试带附件的邮件',
    '请查收附件',
    '/path/to/your/file.pdf'
)

Java示例

import javax.mail.*;
import javax.mail.internet.*;
import java.util.Properties;
import java.io.File;

public class EmailWithAttachment {
    public static void send(String to, String from, String host, 
                          String subject, String text, String attachmentPath) {
        Properties properties = System.getProperties();
        properties.setProperty("mail.smtp.host", host);
        properties.setProperty("mail.smtp.auth", "true");
        properties.setProperty("mail.smtp.starttls.enable", "true");
        properties.setProperty("mail.smtp.port", "587");

        Session session = Session.getDefaultInstance(properties,
            new javax.mail.Authenticator() {
                protected PasswordAuthentication getPasswordAuthentication() {
                    return new PasswordAuthentication(from, "your_password");
                }
            });

        try {
            MimeMessage message = new MimeMessage(session);
            message.setFrom(new InternetAddress(from));
            message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));
            message.setSubject(subject);

            // 创建消息体部分
            BodyPart messageBodyPart = new MimeBodyPart();
            messageBodyPart.setText(text);

            // 创建多部分消息
            Multipart multipart = new MimeMultipart();
            multipart.addBodyPart(messageBodyPart);

            // 添加附件
            messageBodyPart = new MimeBodyPart();
            DataSource source = new FileDataSource(attachmentPath);
            messageBodyPart.setDataHandler(new DataHandler(source));
            messageBodyPart.setFileName(new File(attachmentPath).getName());
            multipart.addBodyPart(messageBodyPart);

            // 设置完整消息
            message.setContent(multipart);

            // 发送消息
            Transport.send(message);
        } catch (MessagingException mex) {
            mex.printStackTrace();
        }
    }
}

2. 使用命令行工具

# 使用mailx发送带附件的邮件
echo "邮件正文" | mailx -s "邮件主题" -a /path/to/attachment.txt recipient@example.com

# 使用mutt发送
mutt -s "邮件主题" -a /path/to/attachment.txt -- recipient@example.com < body.txt