I have a new Exchange 2010 install that is acting as an open relay.
I have 3 receive connectors, Client Servername, Default Servername and Internal Client Relay.
I added the last one to allow the servers within our network to relay via Exchange so our automated applications could send mail both externally and internally. These servers use Perl & Omnimark to do the sending.
I've attached a Word doc with screenshots of our connectors. If I remove the 0.0.0.0-255.255.255.255 from the Internal Client connector which is what I assume I need to do as I only want machines on the internal network to use this, external users can't email internal users as I get:
SMTP error from remote mail server after MAIL FROM:<email@example.com> SIZE=5605:
host mail.letterpart.com [184.108.40.206]: 530 5.7.1 Client was not authenticated
I know I've mucked up one of the others but I can't remember where or why and as I only ever set up an exchange server every 7 years or so and I can't remember what I had for breakfast last week, I'm pretty clueless here.