Jobs at small Cleveland companies nobody posts about - what worked for you?

A friend who works at a local manufacturer says there are openings not advertised online. I have read a lot of threads here and could not find my exact situation. They like a brief email with a résumé. What do you write in a cold email?

Thanks for writing this out. I went through something close to it last year, and it got easier once I kept a simple log of every call and form.