Think of a time when you had to write a negative letter, or when you received one—but not a letter having legal implications, such as terminating employment or threatening disciplinary action. Such a letter should not be discussed in this open forum.
What made the letter effective? What lessened its effectiveness? To what extent did it achieve the goal of conveying unpleasant news, while maintaining the recipient's goodwill? Be sure to mention, and prioritize, all of the factors relevant to your analysis.