In writing emails, blog comments, and messages in discussion groups, there are certain rules to observe.
One of them is not to write in all capital letters. Aside from the difficulty in reading messages written in all capital letters, one other important reason why we do not write in all capital letters is social in nature. Writing in all capital letters is like shouting.
This has been a long-standing netiquette for many years. Unfortunately, there are still those who write emails and post comments in ALL CAPS.
ALL CAPS, if used in abundance or in your entire message, have the same effect like shouting – and nagging. They annoy the wits out of the recipients and readers. Your messages lose their effect as they are completely ignored or deleted. Or, in discussion groups, if you repeatedly use ALL CAPS, you run the risk of being banned.
If all you want is to put emphasis on some parts of your message, use ALL CAPS for those important words only. (Or the other technique is to enclose the *important* words with asterisk like in this sentence.)
If your reason for typing in ALL CAPS is because you find pressing the Shift key to capitalise inconvenient and slows you down, why not use all lower case only.
True, you may not pass your English 101 class when you type in all lower cases, but the practice appears more widely accepted than ALL CAPS. And your message may get across easily. And shall we say, amiably. At least to those who find ALL CAPS offensive.