python中执行smtplib失败怎么解决

import smtplib

from email.mime.text import MIMEText

# 第三方 SMTP 服务

mail_host = "smtp.163.com"  # SMTP服务器

mail_user = "username"  # 用户名

mail_pass = "passwd"  # 密码(这里的密码不是登录邮箱密码，而是授权码)

sender = 'sender_mail@163.com'  # 发件人邮箱

receivers = ['receive_mail@qq.com']  # 接收人邮箱 

content = 'Python Send Mail !'

title = 'Python SMTP Mail Test'  # 邮件主题

message = MIMEText(content, 'plain', 'utf-8')  # 内容, 格式, 编码

message['From'] = "{}".format(sender)

message['To'] = ",".join(receivers)

message['Subject'] = title

try:

    smtpObj = smtplib.SMTP_SSL(mail_host, 465)  # 启用SSL发信, 端口一般是465

    smtpObj.login(mail_user, mail_pass)  # 登录验证

    smtpObj.sendmail(sender, receivers, message.as_string())  # 发送

    print("mail has been send successfully.")

except smtplib.SMTPException as e:

    print(e)