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The court case mentioned simply tells us that the already existing rules of libel will apply to e mails.
The purpose is not to stiffle free speach. It is to protect you and I from untrue statements made might be made about us by others.
As Lawyerboy and Hugmonster point out society has always placed some restrictions on our actions. It leaves us with a balance that provides reasonable people with considerable, but not totally unlimited freedom to say what we would like to say.