Are you too lazy to use Caps Lock?

I have received emails from my friends that are written entirely either in capital letters or in small letters! I have noticed that their emails take longer to read. Readability is hindered when you don't capitalise your emails correctly. Also, it's rude, or it is tantamount to shouting when you write your emails in capital letters.
So, use the caps lock wisely and make your emails better. This need not apply to professional emails alone, but even while writing to friends.