When you have a back-and-forth email "conversation" with someone, and each of you keeps adding to the quoted thread with new information. The email go back and forth like a long-lasting volly during a volleyball game.
"We finally straightened out our misunderstading with an email volley. Of course, if I had just called her, we could have done it in a few seconds."
by Adam Haaretz May 1, 2006