Sending email to many people means there can be errors in sending, and it will be read on many different client and devices. Mailchimp offers you a reliable wa

Sending email to many people means there can be errors in sending, and it will be read on many different client and devices. Mailchimp offers you a reliable way to send, and templates that are pretty well tested. In addition to many more features including sending email at the "right time" for the user. If your problem is only money, and you can trade it for time to deliver, then there are SaaS like Mailup with a different business model, that charge you for speed. You can send to 200k users for free but it will take a lot of time. Next, if you want to save more money and you can build your own template, you can set up a tool like Sendy which is basically a self-hosted (very) simplified mailchimp. That can be used with Amazon SES, or Sendgrid. If you're scared about your domain, just buy one that looks similar enough and open an AWS account in another region. Finally, you can build your own, including integrating in your analytics tools, etc. Again, I'd use SES or Sendgrid or similar, instead of managing my own SMTP server, which is an operational nightmare. (I have no experience with Salesforce Marketing Cloud, that others are referring.)