Advanced Postfix configuration

Looking for experienced Postfix administrator in configuring our Postfix SMTP server for email marketing newsletters and configure the best delivery options to avoid getting blacklisted with major mail servers (yahoo, gmail, hotmail etc). We have a Fedora Core 10 linux server used to send a large list of email newsletters. Postfix is already installed and working "basically" for sending bulk email generated in the same server. We want to configure Postfix to send email using another virtual IP that we have configured on the server to be used for another domain name, besides the main IP address that is used for a different domain name. Emails sent by one domain name must be identified by its own IP address, and emails sent by the other domain name must be identified by the other IP address. So the job includes configuring POSTFIX to accept email delivery from other locations (relay). I don't know if this can be done by a list of permitted IPs or by authenticating user and password. Apply the best configuration options for email delivery of 300.000 emails per day per IP (it is not necessary to do it automatically, we can choose which IP to use en each case), we will probably be using Interspire Email Marketer on the same server or on another server and send throught this server. Check and adjust if needed configuration of mailserver, MX records, SPF, domain keys, etc for the 2 domains hosted on the server. The server is only used to send email for these domain names, the email accounts for these domains are already configured on another server.