What is THE BEST roadmap / course / mentorship FREE or PAID to learn cold email?

I need to learn how to make the most out of cold email.

I need to create a lead gen system for my business (B2B). I'm NOT planning to become a lead gen agency. I need a system that works for me, and it doesn't have to be fancy, but it's gotta have the fundamentals nailed down.

I can't keep reaching out manually to prospects and juggling with different tools. It's not efficient, not scalable and it bothers me not knowing exactly what I'm doing.

I'm a solo guy and I currently have the time and willingness to obsessively focus on this for a month or two (then gradually slow down because I also have to focus on other areas).

I'm a software developer, so I pick up technical concepts and tech stacks relatively fast. But there's a lot of buzzword about cold email and I'm not familiar with the go-to's YT channels, blogs, and goo-roo's who aren't selling snake oil.

Having said this... It really would help me if you dropped your best resources for someone like me, and also I'd appreciate it if you set realistic expectations given the context I've given you.

Thanks!