Hello,
You can try direct mailing to the internet from scripting in your web site.
Your hosting provider might suspend or terminate your service if your emails result in spam complaints.
Newsletter service providers have many benefits besides "sending email". Sending email is easy enough, but they also help you to be a good email sender for example they can handle unsubscribe requests, reputation monitoring, and often provide perks such as templates or social integration.
Yes, you can buy a dedicated server that has a static IP address so that your email is the only email coming from your IP, but to not get blocked as a spammer you'll need to keep the mind some of these
email marketing tips too.
If you still want to go the dedicated server route and need a consultant to build you a Linux server with a static IP please let me know.