I think most of us have been guilty of this at one time or another, I know I have.

When writing chatty emails to friends and family, sending tweets or posting some random event in Facebook, it's easy to get carried away. However, in the business world, excessive punctuation should generally be avoided as it makes you appear amateurish and even a tad hysterical.
By overusing punctuation, you actually achieve the opposite of what you are trying to portray and dilute the effectiveness of exclamation marks and question marks by overusing them. As hard as it may be, try to restrain the impulse to use multiple exclamation marks or question marks. If you truly feel the need for added emphasis, try adding the use of capitals, bolding or italics.
Amber McNaught in her blog
Writing Well makes the following commentary:
"Excessive punctuation. You’ve all seen it. Sentences which end with an entire line of exclamation points. Like this!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!
Why? Why do people do this? I mean, OK, they’re excited, sure. And they want to exclaim about it. But one exclamation point tells me that the writer is excited. An entire row of them doesn’t tell me that they’re really excited. Just that they’re excited, and they don’t know too much about punctuation."
Chandra Stauffer also writes a hysterical blog entry appropriately titled
Punctuation Promiscuity, you can read it
here.
Lastly, I think this
blogger sums it up perfectly:
"One punctuation mark is all that is needed in any situation. If you feel the intensity of your message is not conveyed with one punctuation mark, then you need to go back and revise your sentence. Don't just keep adding punctuation until you feel better."
A good rule to follow in business writing is most business documents can be written without the use of any exclamation marks.