Dear Susan,
I'm writing to offer my warmest congratulations on your being awarded as the Best Employee of your company.Your performance of being diligent and hardworking has made you outstanding,I admire you for your contribution for our company.In addition,your characteristics of being enthusiastic and warm-hearted not only helped and encouraged many collegues,but also promoted the cooperation and uprised our morale.You are the best one worth this award.
Sincere conratulations to you.And I wish you still further success.
Best wishes
Sincerely yours,
XXX