Today’s tip is short and simple.
Avoid using exclamation marks (or exclamation points if you are from the US).
It does not matter how excited you are. It does not matter how informal you are being. A string of exclamation marks immediately marks out your business writing as unprofessional.
When you want to convey excitement, use words. If you feel the situation really merits an exclamation mark (and I have yet to see a business situation that does), limit it to one.
All you need is one!