Self-Hosted Cold Email Setup

I need a self-managed way to reach roughly 2,000 fresh prospects every day for pure lead-generation purposes. Right now I’m working with ordinary free Gmail accounts, so I’m bumping into the standard send limits and the deliverability issues that come with them. I do not want to rely on subscription platforms such as Instantly.ai, Smartlead.ai or any other “black-box” SaaS. Instead, I’m looking for a repeatable system that I own end-to-end and that keeps my monthly costs low.

I am open to any suggestion you would have.