Jobs at small Tucson companies nobody posts about - 7 months and counting

Two small Tucson employers told me they are hiring but have not posted yet. 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?

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