The aim of the email was to encourage crews to release and then reset the parking break at the appointed off blocks time if you were not ready to push as releasing the break sent an ACARS message for your off blocks time. A very dangerous practice in my opinion which much to my surprise some of my colleges were happy to comply with.
Still goes on. It happened to me the other day, Captain requested clearance to release and then re-apply the brakes while we were de-icing so that he could get an on time departure.
