How To Write A Closing In A Letter . When sending cards through the mail, you should always use your physical signature. To close a business letter, it is important to summarize the key points you have made in the letter. sample closing a business letter uniqueb from unique-b.com If the closing is more than one word, use lowercase for any. The message here is “i think we can safely agree how i sign off isn’t the part of this letter that matters.”. So, you can begin with the date of drafting the letter.