old_contents: # -*- coding: utf-8 -*-
  from threading import Thread
  from flask import current_app, render_template
  from flask_mail import Message
  from . import mail
  
  from email import charset
  charset.add_charset('utf-8', charset.SHORTEST, charset.BASE64, 'utf-8')
  
  def send_async_email(app, msg):
      with app.app_context():
          mail.send(msg)
  
  
  def send_email(to, subject, template, **kwargs):
      app = current_app._get_current_object()
      msg = Message(app.config['FLASKY_MAIL_SUBJECT_PREFIX'] + ' ' + subject,
                    sender=app.config['MAIL_SENDER'], recipients=[to],charset='utf-8')##加入该关键字参数，使发送的html支持utf-8编码
      msg.body = render_template(template + '.txt', **kwargs)
      msg.html = render_template(template + '.html', **kwargs)
      thr = Thread(target=send_async_email, args=[app, msg])
      thr.start()
      return thr
  
new_contents: # -*- coding: utf-8 -*-
  from threading import Thread
  from flask import current_app, render_template
  from flask_mail import Message
  from . import mail
  
  from email import charset
  charset.add_charset('utf-8', charset.SHORTEST, charset.BASE64, 'utf-8')
  
  def send_async_email(app, msg):
      with app.app_context():
          mail.send(msg)
  
  
  def send_email(to, subject, template, **kwargs):
      app = current_app._get_current_object()
      msg = Message(app.config['FLASKY_MAIL_SUBJECT_PREFIX'] + ' ' + subject,
                    sender=app.config['MAIL_SENDER'], recipients=[to],charset='utf-8')##加入 charset 该关键字参数，使发送的html支持utf-8编码
      msg.body = render_template(template + '.txt', **kwargs)
      msg.html = render_template(template + '.html', **kwargs)
      thr = Thread(target=send_async_email, args=[app, msg])
      thr.start()
      return thr
  
subject: Update email.py