如何在Python中使用email.message.EmailMessage类处理收到的电子邮件？

import smtplib
from email.message import EmailMessage

msg = EmailMessage()

msg['From'] = 'sender@example.com'
msg['To'] = 'recipient@example.com'
msg['Subject'] = 'Hello from Python!'

msg.set_content('This is the body of the email.')

with open('path/to/attachment.pdf', 'rb') as f:
    attachment_data = f.read()
msg.add_attachment(attachment_data, maintype='application', subtype='pdf', filename='attachment.pdf')

with smtplib.SMTP('smtp.example.com', 587) as smtp:
    smtp.login('username', 'password')
    smtp.send_message(msg)