用PYTHON实现一个邮件类，可以接收邮件，可以发送邮件，可以删除邮件，可以获取未阅读邮件，可以给邮件做标记

这是一个使用 Python 实现的简单的邮件类的示例：

import smtplib
import imaplib

class Email:
    def __init__(self, username, password):
        self.username = username
        self.password = password

    def send_email(self, to, subject, message):
        server = smtplib.SMTP('smtp.gmail.com', 587)
        server.ehlo()
        server.starttls()
        server.login(self.username, self.password)
        server.sendmail(self.username, to, f'Subject: {subject}\n\n{message}')
        server.close()

    def receive_email(self):
        mailbox = imaplib.IMAP4_SSL('imap.gmail.com')
        mailbox.login(self.username, self.password)
        mailbox.select()
        _, search_results = mailbox.search(None, 'UNSEEN')
        if search_results[0]:
            for email_id in search_results[0].split():
                _, msg = mailbox.fetch(email_id, "(RFC822)")
                for response in msg:
                    if isinstance(response, tuple):
                        msg = email.message_from_bytes(response[1])
                        subject = msg['subject']
                        sender = msg['from']
                        print(f'Subject: {subject}\nFrom: {sender}\n')
        mailbox.close()
        mailbox.logout()

    def delete_email(self, email_id):
        mailbox = imaplib.IMAP4_SSL('imap.gmail.com')
        mailbox.login(self.username, self.password)
        mailbox.select()
        mailbox.store(email_id, '+FLAGS', '\\Deleted')
        mailbox.expunge()
        mailbox.close()
        mailbox.logout()

    def mark_as_read(self, email_id):
        mailbox = imaplib.IMAP4_SSL('imap.gmail.com')
        mailbox.login(self.username, self.password)
        mailbox.select()
        mailbox.store(email_id, '+FLAGS', '\\Seen')
        mailbox.close()
        mailbox.logout()

该类实现了五个功能：

1. `send_email` 函数用于发送邮件，接收三个参数：收件人地址、主题和消息正文。

2. `receive_email` 函数用于接收未读邮件，并在控制台输出主题和发件人信息。

3. `delete_email` 函数用于