唉，我的 Mail Server 真的那麼狠嗎？

Transcript of session follows.
 Out: 220 www.t-times.net ESMTP Postfix
 In:  EHLO beauty.cloudmark.com
 Out: 250-www.t-times.net
 Out: 250-PIPELINING
 Out: 250-SIZE 10240000
 Out: 250-ETRN
 Out: 250 8BITMIME
 In:  MAIL From:<nobody@beauty.cloudmark.com> SIZE=491
 Out: 250 Ok
 In:  RCPT To:<abcdef@t-times.net>
 Out: 550 Client host rejected: cannot find your hostname, [66.151.128.164]
 In:  DATA
 Out: 554 Error: no valid recipients
 In:  RSET
 Out: 250 Ok
 In:  QUIT
 Out: 221 Bye