Sometimes it's ok to use uppercase. Capital letters can
add a touch of class to the apperance of your page. However, they
should be used very sparingly. There are three reasons why you should
avoid them in most cases:
It is hard for the human eye to recognize words in
all caps. This is because the shape around each word is the same. All
words in uppercase are rectangular in shape, where words in lowercase
have ascenders and descenders on some letters that vary the shape.
Notice the difference in the shapes of these two words:
See the difference? We recognize words largely based on their
shape. When the shape of all words is the same, it makes it much more
difficult to read them.
Because of the shape of the letters, uppercase has a
tendency to look harsh. Capital letters have a subtly threatening
appearance. When your readers are confronted with a phrase (or even a
single word) in all caps, it is likely to negatively influence them.
Considering that you want visitors to read your copy, this is
definitely not the feeling you want them to have.
Although this issue is important on a website, it's even more
critical in emails. Since emails are more personal, uppercase can feel
even more threatening. Always try to avoid using all caps in emails.
Uppercase is a form of emphasis, but it is very
weak. When you use capital letters to emphasize a particular point, it
will look a little different from the rest of the copy, but there won't
be enough contrast for it to really stand out. It is far better to use
a contrast in size, color or weight (for example, bold the text). These
forms of emphasis are all easier to read, and they stand out much
As I mentioned earlier, there are times when it's appropriate to use uppercase. Just think carefully and use it sparingly.
Just a quick note: You might have noticed that I use uppercase
for the titles of the various sections of this newsletter. The reason
is that it's the only form of emphasis I have, since this is a plain
text newsletter. If I had the option of bolding my headings, I would
definitely do that instead.