I am creating a web application that allows users to send broadcast emails to a list of subscribers. Essentially, it's a mass emailer and autoresponder, like AWeber or Constant Contact or MailChimp.
The server that we were planning on hosting this application on is InMotion Hosting's "Essential" Dedicated Server, I have included the specs on it below in case they are relevant. I have spoken with InMotion Hosting's support and they say that this server can send unlimited emails (no limit) with no extra cost. However, I am unsure if this is really a good solution because people are paying me for this service and therefore I need to give them great deliverability, and it has to be reliable and not get shut down or blacklisted, because then I can't provide customer's what they are paying for. I also don't know if it's smarter (for spam reasons) to have multiple IP addresses to send from, and if so, I don't know if it's possible to split a server into multiple SMTP IP addresses?
I have seen other third party services out there, such as sendgrid and mailgun, but they are too expensive to work within our price point (they would literally take about 25% or revenue). The question I can't seem to find the answer to is how I could eliminate this potential cost by doing it myself, using our own server. I want to know what I need to do to be able to have a high quality email sender without the PER EMAIL costs! If it's something that is a static monthly cost, that's actually ok in this situation, I just don't like the PER-EMAIL cost because it forces me to put limits on things. Thanks in advance for any help!
Server Specs: Intel® Core® E2220/E5400 2C/2T, 2GB RAM 2x160GB HDD, 4TB Data Transfer