MTA Setup on linux server for high volume e-mail delivery.

The idea is this: - Linux server already installed (Gentoo dist, upto date) – if necessary we prefer not to change this as our admins are already familiar with the environment. - Web/MySQL servers running to run the PHP Mailer software backend. - Mailer software can be configured to use sendmail style calls or SMTP calls for mail sending. - What we need: o Configure an MTA (we don’t have a preference at this point. We have some experience with qmail, but are not fanatics we just want the best send performance). o Optimize the machine for sending speed. o We need a way to measure the throughput as well as indicate bottlenecks in memory, cpu, network, etc. o Optimize MTA settings for DNS, SPF, SenderID, DomainKeys and DKIM on server for efficient sending to all major email servers such as Yahoo, hotmail, AOL, etc o This server will handle multiple domains as we occasionally send for clients. What is required? Add a reference to our mail server on clients DNS MX? Etc… - Finally, we would like a script/guide to follow in order to configure other future servers. We have currently obtained about 15 - 20 e-mails sent per second on our "out of box" systems, we are looking for a significant boost in performance. We are running on new hardware, with lots of bandwidth. According to the reports generated we may work together to augment machine specs and/or bandwidth if this is shown to be a bottleneck.