1. 首先要导入所需的库，包括imaplib、email、os等：

import imaplib
import email
import os

2. 设置IMAP服务器信息和登录凭据：

mail = imaplib.IMAP4_SSL('imap.gmail.com')
mail.login('youremail@gmail.com', 'yourpassword')
mail.select('inbox')

3. 使用搜索条件筛选出要处理的邮件，比如搜索所有未读邮件：

result, data = mail.search(None, "UNSEEN")

4. 遍历搜索结果，提取邮件正文和附件：

for num in data[0].split():
    typ, data = mail.fetch(num, '(RFC822)')
    msg = email.message_from_bytes(data[0][1])
    
    # 读取邮件正文
    if msg.is_multipart():
        body = ""
        for part in msg.walk():
            ctype = part.get_content_type()
            cdispo = str(part.get('Content-Disposition'))

            if ctype == 'text/plain' and 'attachment' not in cdispo:
                body = part.get_payload(decode=True).decode('utf-8')
    else:
        body = msg.get_payload(decode=True).decode('utf-8')
        
    # 遍历所有附件
    for part in msg.walk():
        ctype = part.get_content_type()
        cdispo = str(part.get('Content-Disposition'))

        # 判断是否是附件
        if ctype == 'application/octet-stream' and 'attachment' in cdispo:
            filename = part.get_filename()

            # 保存附件到指定目录
            if filename: 
                filepath = os.path.join('/path/to/folder', filename)
                with open(filepath, 'wb') as f:
                    f.write(part.get_payload(decode=True))

其中，'/path/to/folder'是你要把附件保存到的目标目录。

5. 标记已读邮件：

for num in data[0].split():
    mail.store(num, '+FLAGS', '\\Seen')