Layoffs at work are forcing me to job hunt a few months before I planned. I'm in a good spot and a have a large network of friends/associates in my field but I am far outside of my comfort zone.

A few former colleagues have offered to submit my resume to their companies for an open positions -- which is awesome.

Do I attach a cover letter with my resume or does an email to the former colleague count as the cover letter? My contacts are all manager level, like me. The emails I'm writing are professional in nature and cover the material found in cover letters.