Hello,

i am facing problem with "wilson-acc.com" domain b,coz my user not able to send user@wilson-acc.com
but when i send through yahoo.com it working and not delivery failed message comes.
i have test with network-tools.com and valid email address it say "Could not verify recipient".

form users@wilson-acc.com to my user@mydoman.com mail received perfectly.
what is the issues 

this is my delivery failed message

From: Content-filter at mail.wilson-acc.com [mailto:postmaster@mail.wilson-acc.com]
Sent: Saturday, December 04, 2010 5:46 PM
To: gian.pawar@mydomain.com
Subject: Undeliverable mail, MTA-BLOCKED

The message WAS NOT relayed to:
  <Alita.wang@wilson-acc.com>: [127.0.0.1] said:
   451 4.5.0 From MTA([127.0.0.1]:10025) during fwd-rundown-1 (Negative SMTP response to RSET: 421 Unexpected failure, please try later at (eval 84) line
1143.): id=25388-09
  <kelly.chu@wilson-acc.com>: [127.0.0.1] said:
   451 4.5.0 From MTA([127.0.0.1]:10025) during fwd-rundown-1 (Negative SMTP response to RSET: 421 Unexpected failure, please try later at (eval 84) line
1143.): id=25388-09
  <sharon.guo@wilson-acc.com>: [127.0.0.1] said:
   550 5.1.0 Failed, id=25388-09, from MTA([127.0.0.1]:10025): 550 unknown user

This nondelivery report was generated by the program amavisd-new at host mail.wilson-acc.com. Our internal reference code for your message is 25388-09/xuiX4m7TYNhn

Return-Path: <gian.pawar@mydomain.com>
From: "gian pawar" <gian.pawar@mydomin.com>
Message-ID: <00ab01cb93ac$f669add0$e33d0970$@mydomain.com>
Subject: FALL 11 TRIMS