Hello, I installed a mail server (exchange 2008) on a domain controller. When I am trying to send mails, those are usually working. But some of the recipients cannot get the messages, because this exchange server got the following error: 421 4.4.0 Remote Server Response was not RFC conformant. This server is a domain controller as well with name xxx.hu. There is a mail.zzz.hu domain name configured to route to this server (the reverse ip configured as well for this name). My question is, that what I need to configure to solve this problem. Thank you in advance. Andras

I have few similar threads for you.421 4.4.0 REmote server response was not RFC conformanthttp://social.technet.microsoft.com/Forums/en-US/exchangesvrtransport/thread/aca4759d-5baf-4e7c-a6b5-ab5528a8e8c6SMTP 421 4.4.2 Connection Droppedhttp://social.technet.microsoft.com/Forums/en-US/exchangesvradmin/thread/27df11c0-2de8-4b6d-9ce7-d5e424c11addSmtpResponse Membershttp://msdn.microsoft.com/en-us/library/microsoft.exchange.data.transport.smtp.smtpresponse_members.aspxArun Kumar | MCSE - 2K3 + Messaging | ITIL-F V3

hi,421 4.4.0 must be a DNS problem. please check your DNS status...regards,Exchange - MVP | www.cozumpark.com | www.mumincicek.com

hi Arun,maybe the problem was solved by him but there is no feedback to forum...thanksregards,Mumin CICEK | Exchange - MVP | www.cozumpark.com | www.mumincicek.com