#5 - April 5, 2007, 3:56 a.m.
Trial accounts have a limited number of whispers they can send. We still want new players, even those on trial accounts, to have the ability to converse with friends, speak with our in-game support if necessary, and experience as much of the game as possible. We're taking the issues seriously, but removing the whisper ability from trial accounts would only move the problem, not remove it. I don't have any statistics, but I wouldn't be surprised that a good portion of those sending the whispers weren't on trial accounts at all.
You can see what restriction Trial accounts have here:
http://www.blizzard.com/support/wowbilling/?id=abl01925p