In writing, punctuation carries much of this suggested interpretation of the mere words. If you omit it completely, alter it or place punctuation marks sloppily, the reader can be puzzled or, without much pondering, misinterpret what you write all too easily.
Of course, mistakes can happen; there's nothing dramatic about that. The absence of rules should just be the exception, not itself the rule.
So, together with avoiding too much slang in your emails,
- try to follow the rules of punctuation
to both your and the reader's benefit and understanding.
No Punctuation Mark Reduplication
Nothing is classier, of course, than the skillful hyperbole, say in exclamation marks!!!!111!!
There is also a proper place for every form of art, however — and professional emails are usually not the right place for many exclamation or question marks. Strive for very few exclamation marks, and don't reduplicate other punctuation marks, even if they are in their proper place.