Jobs at small Tulsa companies nobody posts about

A friend who works at a local manufacturer says there are openings not advertised online. I have been trying to stay organised about it. They like a brief email with a résumé. What do you write in a cold email?

Small employers often hire on recommendation. Ask neighbours, former co-workers and your library.

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