@dp.message_handler(lambda message: message.text.isdigit(), state=Form.password)
async def send_emai(message: types.Message, state: FSMContext):
    await Form.next()
    await state.update_data(password=int(message.text))
    await bot.send_message(message.chat.id, "Укажите email: ")

@dp.message_handler(lambda message: not "@" in message.text, state=Form.email)
async def check_email (message: types.Message):
    return await message.reply("Некорректно введен email.\nУкажите email: ")