@vonny,
I was kidding in my way when I said Nah.. because all caps is considered shouting.
Sometimes, though, people do it because they have vision problems themselves and haven't figured out how to enlarge letters just for themselves. I think you can type something out, and then look at it with your computer's equivalent of my computer's View in my safari toolbar, to see if you (they, with vision problems) haven't gummed up spelling.