Python如何实现Flask异步发送邮件

from flask import Flask
from config import Config
from flask_sqlalchemy import SQLAlchemy
from flask_mail import Mail

db = SQLAlchemy()
mail = Mail()

def create_app():
  app = Flask(__name__)
  app.config.from_object(Config)
  db.init_app(app)
  mail.init_app(app)   from .controller import controller
  app.register_blueprint(controller)

  return app

from flask import current_app, render_template
from flask_mail import Message
from threading import Thread
from main import mail

def send_async_email(app, msg):
  with app.app_context():
    mail.send(msg)

def send_email(to, subject, template = 'index', **kwargs):
  app = current_app._get_current_object()
  msg = Message(subject, sender = app.config['MAIL_USERNAME'], recipients = [to])
  msg.html = render_template('{}.html'.format(template), **kwargs)
  thr = Thread(target = send_async_email, args = [app, msg])
  thr.start()
  return thr