I often find telnet a good way to diagnose SMTP problems.
Our Exchange 2007 environment has multiple AD sites each with their own Hub Transports.
Should I be able to send mail via telnet from one HT to another? Although I can initially telnet on port 25 to another Hub Transport server, I am unable to actual send SMTP mail.
Once i get to :
MAIL FROM: firstname.lastname@example.org
I get an error saying that
"530 5.7.1 Client was not authenticated"