Dear …
RE: Winner of __(Name of Contest)__
Congratulations for winning the __(Name of contest)__contest! As our top __(salesperson/customer service rep/etc.)__ this __(year/month/etc)__, it is our pleasure to present you with __(type of prize)__. Your achievement of __(briefly describe what was achieved)__ is outstanding and it’s an honor for us to be able to reward your amazing efforts. We are delighted to see how you rose to the challenge, __(Name)__. You certainly have a great future in __(type of field)__ and we are proud to have you __(in our organization/on our team/etc.)__. No doubt we will be seeing more of your successes in the future. Again, congratulations! You are very deserving of this __(award/prize.)__.
Yours truly,