用PYTHON实现一个工具类，可以接收邮件，可以发送邮件，可以删除邮件，可以给邮件做标记

你可以使用 Python 的 `imaplib` 模块和 `smtplib` 模块来实现这些功能。

下面是一个示例代码，实现了接收、发送、删除和标记邮件的功能：

import imaplib
import smtplib
import email

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

    def connect(self):
        self.imap_client = imaplib.IMAP4_SSL(self.host)
        self.imap_client.login(self.username, self.password)

    def disconnect(self):
        self.imap_client.close()
        self.imap_client.logout()

    def send_email(self, to, subject, body):
        message = f"""\
From: {self.username}
To: {to}
Subject: {subject}

{body}
"""
        smtp_client = smtplib.SMTP_SSL(self.host)
        smtp_client.login(self.username, self.password)
        smtp_client.sendmail(self.username, to, message)
        smtp_client.quit()

    def fetch_unread_emails(self):
        self.imap_client.select('INBOX')
        _, msg_ids = self.imap_client.search(None, 'UNSEEN')
        msg_ids = msg_ids[0].split()
        return [self._fetch_email(msg_id) for msg_id in msg_ids]

    def _fetch_email(self, msg_id):
        _, msg_data = self.imap_client.fetch(msg_id, "(RFC822)")
        msg = email.message_from_bytes(msg_data[0][1])
        return {
            'subject': msg['subject'],
            'from': msg['from'],
            'to': msg['to'],
            'body': msg.get_payload()
        }

    def delete_email(self, msg_id):
        self.imap_client.store(msg_id, '+FLAGS', '\\Deleted')
        self.imap_client.expunge()

    def mark_as_read(self, msg_id):
        self.imap_client.store(msg_id, '+FLAGS', '\\Seen')

# 使用方法示例
email_client = EmailClient("imap.example.com", "username", "password")
email_client.connect()

# 发送邮件
email_client.send_email("to@example.com", "Subject", "Body")

# 获取未读邮件