Our domain is hosted with a cPanel based shared hosting company only for website.
We have an Exchange 2003 server that is assigned with two dedicated IP's provided by our ISP with rDNS configured. So all outgoing emails are send using these two ISP lines and all works fine.
Since we are going to change the ISP, and the new ISP is refusing to set rDNS we are going to use our cPanel based shared hosting account to send our mails - so we will be configuring our Exhcnage 2003 to [smarthost] to forward all the emails to the hosting server.
I need to what I have to do in the cPanel account to make this work.
Well, nothing really, you could setup another email account and use that though, in place of the default cpanel username and password.
So you'd just setup the smarthost on exchange and use basic authentication (cpanel username + password or [email protected] + that password). The host to connect to would be your cpanel servers hostname/ip address or just use your domain name, if it points there.