In one sentence, describe what the following article is about:

The letter may become part of future legal proceedings. Regardless of how upset you may be regarding unfair accusations or possible threats contained in the demand letter, respond with calm and accurate language. Never try to match threats with anyone, as this can cloud the issues involved for a judge or jury that may have to evaluate a later lawsuit. Whatever you do, be sure to respond both promptly and politely. The three most common responses to a demand letter include: (1) truthfully denying that you have breached the contract, (2) asserting an affirmative defense indicating that circumstances beyond your control prevented you from acting, or (3) apologizing for your actual error and asking if you can “cure” or “fix” the breach in a specific way by a new, mutually agreeable date. Keep in mind that if you do provide an acceptable affirmative defense, you will still need to propose an agreeable way to “cure” the unavoidable breach. Carefully quote the terms of your contract and attach documentary proof, if necessary, that clearly indicates how you upheld your duties or which circumstances beyond your control prevented you from timely handling them. Unless you’re determined to get out of the contract and have your lawyer file a lawsuit, politely suggest alternative ways you can readily “cure” any perceived contract breach.  Remember to include notation of any errors included in the initial demand letter. Correct any factual errors but be sure to keep the tone calm and professional. Properly format your letter. Make the correspondence as professional as possible. Make one copy of your reply for each party and one for yourself. For example, if there are two Plaintiffs, you should make three copies, one for each of them, and one for yourself.

Summary:
Respond carefully. Decide on the tone and type of response you will send. Write your response letter. Print, sign, and prepare your letter for mailing.