Hi,
You contradicted yourself in the project description - you said that the cheapest and most reliable person will get the job. Those 2 don't go together, but if you want reliable I could be your guy.
I run multiple mail servers on Ubuntu, mostly using postfix which is a good match for your needs.
I can set this up along with generating a shell script to repeat the process for you.
You understand the spam issue which is a genuine concern if you will be sending mainly newsletters as these do often get flagged as spam and give a negative hit on your IP address.
But if all your recipients expect and want your emails then your IP reputation will increase over time.
Assuming that your newsletters are opt-in customers and you are not sending huge volumes I would also recommend Mandrill, it is the mail deliver engine behind Mailchimp. Free to use for 12,000 emails per month and they are world leaders at getting emails straight to inboxes.
Only downside is they have no tolerance for bad email lists - all addresses must exist and work to avoid spam complaints. Mandrill could either replace the need for your own mailserver or work in combination with it.
Regards,
Mark