An email list belongs to you. No algorithm decides who sees your message, and no platform can take your contacts away. This page covers what you need to get started: the right tool, a clean sign-up and the first emails that run on their own.
I send my own newsletter with Listmonk, open-source software that runs on my own servers. These articles show what a setup like that looks like and where a hosted service gets you there faster.
If you send marketing emails, you need your subscribers' consent. The article on double opt-in explains how a sign-up with a confirmation email works. This page is not legal advice.