如何按时间顺序重新排序mbox文件？

import email
import datetime
import os

def parse_mbox(file_path):
    with open(file_path, 'rb') as f:
        msg = email.message_from_bytes(f.read())
        messages = []
        for part in msg.walk():
            if part.get_content_type() == 'message/rfc822':
                messages.append(email.message_from_bytes(part.get_payload()))
        return messages

def sort_messages(messages):
    return sorted(messages, key=lambda x: x['date'])

def generate_mbox(messages, output_path):
    with open(output_path, 'wb') as f:
        for msg in messages:
            f.write(b'From - ' + msg['from'].encode() + b'\n')
            f.write(b'Subject: ' + msg['subject'].encode() + b'\n')
            f.write(b'Date: ' + msg['date'].encode() + b'\n')
            f.write(b'\n' + msg.as_bytes() + b'\n')

def sort_mbox(input_path, output_path):
    messages = parse_mbox(input_path)
    sorted_messages = sort_messages(messages)
    generate_mbox(sorted_messages, output_path)

input_path = 'input.mbox'
output_path = 'output.mbox'
sort_mbox(input_path, output_path)