[estreeper]

I hate to recommend what is just another service provider, but there are many cloud hosting providers that offer email sending (i.e. AWS, GCP, etc.) and dedicated email companies (Sendgrid, Mailgun, etc.). The cost to send email via any of these services is a tiny fraction of the amount you would pay to Mailchimp.

The value in what Mailchimp does is not so much just sending email, but in all the things around it, like managing subscribers, tracking opens, easily creating nice-looking emails that look good in a variety of mail clients, etc.

Contrary to some of the replies you've received here, it definitely is possible to run your own mail server with good deliverability, and we routinely did this for companies, even fairly small ones, physically on-prem and in datacenters, and cloud. It is not trivial, but far from impossible, and will likely involve communicating with a human when getting a static IP to find a good one. With that being said, I do not recommend you run your own mail server starting out, that is probably not the problem you are trying to solve.