I understand the upper case letters are often referred to as yelling , but I think that is really a bogus way of looking at it. I personally don't care if a reply is in upper or lower case, yelling or emphasizing is done with an exclamation symbol. It's only since the internet and texting became mainstream that uppercase letters are considered by some to be yelling. If I tell someone to Be quiet! it is exactly the same according to some as saying BE QUIET. Proper spelling and using punctuation has gone for a proverbial dump since texting and the internet have evolved. Hence things like omg, ttyl, lmfao, and the list goes on. It used to be capital letters were just a bolder way to show what you were saying or selling. In the advertising business it's called highlighting your ad. So not every uppercase word is yelling.