help help help

u572

"220 host134.host134-server.com ESMTP Sendmail 8.12.10/8.12.10; Thu, 27 Sep 200704:07:11 -0400"
It seems that port25 is filtered on your connection, limiting you to use your ISPs SMTP, so please contact them and ask them to provide you with an alternative SMTP

   上述是一国外ISP 对我的某个信箱能收不能发的解释， 端口25 我这里正常， 信箱昨天以前一切正常。今天开始出能收， 不能发的问题。

host134.host134-server.com 是何东东？ 谁管的， 电信吗？