[Mail] 关于(#5.1.2)错误

[weixin_38073737]

在年前发送没有任何问题,过年回来后,即出现找不到主机的错误, 但PING该域名没有问题,对方发送过来的邮件也可以正常收到. 不知是何原因,域名解析都正常啊.
谢谢各位大虾了.
Hi. This is the qmail-send program at **.com.
> I'm afraid I wasn't able to deliver your message to the following addresses.
> This is a permanent error; I've given up. Sorry it didn't work out.
>
> <[e-mail]>:
> Sorry, I couldn't find any host named mail.com. (#5.1.2)