Python发邮件程序部署到Linux云服务器上之后无法获取邮件服务器的连接

import smtplib
import traceback
from email.mime.text import MIMEText
from email.header import Header

sender = '' # 发送者邮箱
receiver = '' # 接收者邮箱
subject = '放假通知' # 邮件主题
smtpserver = "smtp.163.com" # smtp服务器
username = '' #发送者邮箱账号
password = '' #发送者邮箱密码

try:
    msg = MIMEText('大家关好窗户', 'plain', 'utf-8')  # 中文需参数‘utf-8'，单字节字符不需要
    msg['Subject'] = Header(subject, 'utf-8')
    msg['From'] = sender
    msg['To'] = receiver
    smtp = smtplib.SMTP()
    smtp.connect(smtpserver)
    smtp.login(username, password)
    smtp.sendmail(sender, receiver, msg.as_string())
    smtp.quit()
except smtplib.SMTPException:
    traceback.print_exc()
    print("Error: 无法发送邮件")

这段代码在本地测试都没有问题，只要部署到云服务器上就无法获取连接，最后发现有人连接的时候用了SSL，获取邮件服务器连接时需要改成smtplib.SMTP_SSL()