When writing a letter to your mortgage company with regards to a potential loan modification, you want to make sure first and foremost that you have an accurate mailing address and you know who to make your to.  Many banks are overwhelmed with requests and you do not want to lose valuable time in the mail by not double checking the appropriate mailing information. Make sure your letter includes your loan number, property address, date, your name, and your signature. 

There is not much need for fluff here, so just explain why you need a loan modification and with supporting facts.  The letter alone will only get you in the door to a loan modification application, so save the heavy words and financials for the application and negotiations process.