I have setup a W2003 DC running DNS and DHCP with the domain name of priorynetworks.local. I have installed Exchange 2003 and configured the recipients default policy to use a domain of priorynetworks.co.uk and ran the Internet Mail Wizard to setup an SMTP connector which will send mail using DNS rather than smarthost.
I can send e-mail internally and receive external mail no problem,but when I try and send external mail it just sits in the queue and gives an error of "The connection was dropped by the remote host"
I am able to resolve mx records for domains on the server and telnet using port 25 to mail servers on the Internet. I have also created a PTR record for 22.214.171.124 mailserver.priorynetworks.co.uk which is the external IP address of my Internet connection.
I can't think of anything else which would stop mail from being routed externally, any ideas?