This is an article by Lincoln Murphy and he says: "I call this tactic co-outreach and it’s a combination of the now-common cold outreach emails we all know and love and co-marketing (but with much less overhead, setup, coordination, etc.).
Oh, and it’s super-simple and disgustingly effective. Your mileage may vary, but it’s probably worth the trip.
Okay, so here is the co-outreach tactic in 5 simple steps..."