在新等，急急急 。。。。最近 server上一直在刷smtp的这个认证失败提示

[0FD0:0008-102C] 2017-05-16 14:47:32   SMTP Server: 187-163-143-227.static.axtel

.net (187.163.143.227) connected

[0FD0:0008-102C] 2017-05-16 14:47:33   SMTP Server: Authentication failed for us

er bart ; connecting host 187.163.143.227

[0FD0:0008-102C] 2017-05-16 14:47:33   SMTP Server: 187-163-143-227.static.axtel

.net (187.163.143.227) disconnected. 0 message received

最近 server上一直在刷smtp的这个认证失败提示，认证的用户不是我们内部用户，这是受攻击了么？