Closing the Letter. Choose a Closing: One must use a proper closing in a business letter. Use a comma (,) after it. Sign the Letter: Always sign the letter in ink. If sending a printed copy, always affix the scanned signature. Make Note of Enclosure: One must properly enclose a list of attached documents with the letter. One can use the abbreviation of the enclosure, i.e., Encl. or Enc.
Anything that you'd use in an informal communication is inappropriate for a business letter. This includes slang, text_speak, emojis, and anything off_color or casual. If you're used to communicating mostly with friends, family, or even co_workers you've worked with for a long time, an appropriate closing for a business letter will probably feel pretty stilted at first. Don't worry about it – your colleague or business associate won't feel that way when he or she reads your correspondence. What seems unnatural to you will feel respectful and polite to the recipient.