邮件发送失败，554 DT:SPM 发送的邮件内容包含了未被许可的信息,或被系统识别为垃圾邮件.请检查

看下我的代码哪有问题
错误是554如上；
`from smtplib import SMTP
from email.header import Header
from email.mime.text import MIMEText

def main():
# 请自行修改下面的邮件发送者和接收者
sender = 'initsself@163.com'
receivers = ['278617803@qq.com']
message = MIMEText('554 DT:SPM 发送的邮件内容包含了未被许可的信息，或被系统识别为垃圾邮件。请检查是否有用户发送病毒或者垃圾邮件；', 'plain', 'utf-8')
message['From'] = Header( "wumianinitsself@163.com", 'utf-8')
message['To'] = Header("qishi278617803@qq.com", 'utf-8')
message['Subject'] = Header('示例代码实验邮件', 'utf-8')
smtper = SMTP('smtp.163.com')
# 请自行修改下面的登录口令
smtper.login(sender, 'xxxxxxx')
smtper.sendmail(sender, receivers, message.as_string())
print('邮件发送完成!')

if name == 'main':
main()`

Start by reviewing the inline Python SMTP example, especially the connection, login, message construction, and sendmail call, then compare the reported 554 response with the provider's rejection guidance. Done means determining whether the failure comes from the code or the provider's spam/content policy and documenting the needed correction.