Hello, I am trying to configure exchange 2003 to send outbound email to my isp's smtp server. I have set everything up as I think I should have but I am getting "An SMTP Protocal error occured" in the outbound que. I also get this error from diagnostics logging :Event Type:WarningEvent Source:MSExchangeTransportEvent Category:SMTP Protocol Event ID:7002Date:7/3/2009Time:7:51:12 AMUser:N/AComputer:SERVER-GDescription:This is an SMTP protocol warning log for virtual server ID 1, connection #1. The remote host "74.208.5.2", responded to the SMTP command "mail" with "421 dns lookup failed for sender domain ". The full command sent was "MAIL FROM:<Administrator@guckel.local> SIZE=1187 ". This may cause the connection to fail. now that IP address is not that of my isp it is smtp.perfora.net.any ideas? The same settings I have in the smtp connector work in my outlook client for smtp...Thanks,Ernst.

It looks like your ISP is verifying the validity of your SMTP domain. Based on what I can see from the event log entry you posted, you sent a mail from Administrator@guckel.local. This is not a valid SMTP address on the Internet, so your ISP is rejecting it.Can you change your Administrator's default SMTP address to a valid address? Jim McBee - Blog - http://mostlyexchange.blogspot.com

You're awesome... Hit it right on the head. Thanks for your help. It is much appreciated. Ernst.