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

A friend who works at a local manufacturer says there are openings not advertised online. I would rather hear the honest version than the polite one. They like a brief email with a résumé. What do you write in a cold email?

A short email with two sentences about what you can do and your résumé attached worked for me. I followed up after a week.

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