old_contents: """
  StatsMailer extension sends an email when a spider finishes scraping.
  
  Use STATSMAILER_RCPTS setting to enable and give the recipient mail address
  """
  
  from scrapy import signals
  from scrapy.mail import MailSender
  from scrapy.exceptions import NotConfigured
  
  class StatsMailer:
  
      def __init__(self, stats, recipients, mail):
          self.stats = stats
          self.recipients = recipients
          self.mail = mail
  
      @classmethod
      def from_crawler(cls, crawler):
          recipients = crawler.settings.getlist("STATSMAILER_RCPTS")
          if not recipients:
              raise NotConfigured
          mail = MailSender.from_settings(crawler.settings)
          o = cls(crawler.stats, recipients, mail)
          crawler.signals.connect(o.spider_closed, signal=signals.spider_closed)
          return o
  
      def spider_closed(self, spider):
          spider_stats = self.stats.get_stats(spider)
          body = "Global stats\n\n"
          body += "\n".join(f"{i:<50} : {self.stats.get_stats()[i]}" for i in self.stats.get_stats())
          body += f"\n\n{spider.name} stats\n\n"
          body += "\n".join(f"{i:<50} : {spider_stats[i]}" for i in spider_stats)
          return self.mail.send(self.recipients, f"Scrapy stats for: {spider.name}", body)
  
new_contents: """
  StatsMailer extension sends an email when a spider finishes scraping.
  
  Use STATSMAILER_RCPTS setting to enable and give the recipient mail address
  """
  
  from scrapy import signals
  from scrapy.mail import MailSender
  from scrapy.exceptions import NotConfigured
  
  class StatsMailer:
  
      def __init__(self, stats, recipients, mail):
          self.stats = stats
          self.recipients = recipients
          self.mail = mail
  
      @classmethod
      def from_crawler(cls, crawler):
          recipients = crawler.settings.getlist("STATSMAILER_RCPTS")
          if not recipients:
              raise NotConfigured
          mail = MailSender.from_settings(crawler.settings)
          o = cls(crawler.stats, recipients, mail)
          crawler.signals.connect(o.spider_closed, signal=signals.spider_closed)
          return o
  
      def spider_closed(self, spider):
          spider_stats = self.stats.get_stats(spider)
          body = "Global stats\n\n"
          body += "\n".join(f"{k:<50} : {v}" for k, v in self.stats.get_stats().items())
          body += f"\n\n{spider.name} stats\n\n"
          body += "\n".join(f"{k:<50} : {v}" for k, v in spider_stats.items())
          return self.mail.send(self.recipients, f"Scrapy stats for: {spider.name}", body)
  
subject: Update scrapy/extensions/statsmailer.py