I want to write a letter that is compelling. My realtor says he's not allowed to attach letters to offers because he can lose his license.Focus on three things: State your intentions, show that you have the financial means to make the purchase and make a personal appeal to the seller. Consider the pros and cons of writing a house offer letter in real estate transactions. Learn when to write a letter and when to avoid one. Learn how to write a house offer letter that will be sure to make you stand out from the competition. What you want to change about the house. No, it is not appropriate to write a letter to the seller when making an offer on their house. An authentic offer letter from buyer to seller can make a big difference in whether your bid is accepted. Here are a few do's and don'ts.