如何根据条件转发电子邮件？

import imaplib
import email
from email.header import decode_header

def forward_email(email_address, password, target_email):
    mail = imaplib.IMAP4_SSL('imap.gmail.com')
    mail.login(email_address, password)
    mail.select('inbox')

    _, data = mail.search(None, 'ALL')
    mail_ids = data[0].split()

    for mail_id in mail_ids:
        _, msg_data = mail.fetch(mail_id, '(RFC822)')
        for response_part in msg_data:
            if isinstance(response_part, tuple):
                msg = email.message_from_bytes(response_part[1])

                # 设置转发条件
                if 'important' in msg['Subject'].lower():
                    with open('temp_email.eml', 'wb') as f:
                        f.write(msg.as_bytes())

                    # 使用SMTP转发邮件
                    smtp_server = smtplib.SMTP('smtp.gmail.com', 587)
                    smtp_server.starttls()
                    smtp_server.login(email_address, password)
                    with open('temp_email.eml', 'rb') as f:
                        smtp_server.sendmail(email_address, target_email, f.read())
                    smtp_server.quit()

    mail.logout()

# 示例调用
forward_email('your_email@gmail.com', 'your_password', 'target_email@example.com')