"Send an e-mail in all UPPER-CASE. Use of upper-case words is the equivalent of shouting in some one's ear. ONLY use upper-case words when trying to make a point (such as I just did). Even at that, you should be careful with who you are exchanging messages"
Check out www.iwillfollow.com/email.htm for email
etiquette. Halfway down you will find this quote.
There's your proof, do as you will with it.