Hi all This is my scenario: 1) A box with exchange 5.5 sp4 running NT 4.0 in a nt domain, (this server already have another X400 running between to exchange 5.5.). 2) A box with exchange 2003 sp1, Windows 2003 sp1 Enterprise Edition in Active Directory. I already create the x400 and sent test message with the x400 format but this connection is failing, no e-mail is sent between the two exchange server, I set the monitor log for MT X400, I don't really understand if it is displaying an error on the appl log or system log from NT, the x400 logs are not clear.. I check the log in the mtadata(exchange 2003) and no error is display Can someone help me with this error. THANK YOU...