Как сделать телеграм бот для рассылки?

import logging
import os
import sqlite3
from telegram.ext import Updater, CommandHandler, MessageHandler, Filters
import time

logging.basicConfig(format='%(asctime)s - %(name)s - %(levelname)s - %(message)s',
                    level=logging.INFO)

logger = logging.getLogger(__name__)

# Create a connection to the SQLite database and a cursor to execute queries
conn = sqlite3.connect('mailing_list.db')
c = conn.cursor()
# Create the subscribers table if it doesn't already exist
c.execute('''CREATE TABLE IF NOT EXISTS subscribers (id INTEGER PRIMARY KEY, username TEXT)''')
conn.commit()

TOKEN = os.environ['TELEGRAM_BOT_TOKEN'] = '5898965789:A6575757Gs933Rajo6755464564'



def send_mailing(update, context):
    # Create a connection and cursor for this thread
    conn = sqlite3.connect('mailing_list.db')
    c = conn.cursor()
    # Get a list of all subscribers from the database
    subscribers = c.execute('''SELECT * FROM subscribers''').fetchall()
    # Iterate over the subscribers and send them a message
    for subscriber in subscribers:
        context.bot.send_message(chat_id=subscriber[0], text='Это тестовая рассылка')
        time.sleep(1)  # pause for 1 second before sending the next message
    # Respond to the user who sent the command
    update.message.reply_text('Рассылка отправлена!')

    # Close the connection and cursor
    c.close()
    conn.close()


# Define a function to remove a user from the subscribers list
def unsubscribe(update, context):
        # Create a connection and cursor for this thread
    conn = sqlite3.connect('mailing_list.db')
    c = conn.cursor()
    # Delete the user from the subscribers table
    c.execute('''DELETE FROM subscribers WHERE id=?''', (update.effective_user.id,))
    conn.commit()
    # Respond to the user who sent the command
    update.message.reply_text('Вы были удалены из списка рассылки!')
        # Close the connection and cursor
    c.close()
    conn.close()
# Define a function to add a user to the subscribers list
def subscribe(update, context):
            # Create a connection and cursor for this thread
    conn = sqlite3.connect('mailing_list.db')
    c = conn.cursor()
    # Insert the user's ID and username into the subscribers table
    c.execute('''INSERT INTO subscribers (id, username) VALUES (?, ?)''', (update.effective_user.id, update.effective_user.username))
    conn.commit()
    # Respond to the user who sent the command
    update.message.reply_text('Вы добавлены в список рассылки!')
        # Close the connection and cursor
    c.close()
    conn.close()


def error(update, context):
    logger.warning('Обновление "%s" ошибка "%s"', update, context.error)

updater = Updater(TOKEN, use_context=True)

dp = updater.dispatcher

dp.add_handler(CommandHandler('mailing', send_mailing))
dp.add_handler(CommandHandler('subscribe', subscribe))
dp.add_handler(CommandHandler('unsubscribe', unsubscribe))

dp.add_error_handler(error)

updater.start_polling()
updater.idle()