The Complimentary Close: It is a humble way of ending a letter. It is written in accordance with the salutation. The most generally used complimentary close are Yours faithfully, Yours sincerely, and Thanks & Regards. Signature and Writer’s Identification: It includes signature, name, and designation of the sender. It can also include other details like contact number, address etc. The signature is handwritten just above the name of the sender. Enclosures: Enclosures show the documents attached to the letter. The documents can be anything like cheque, draft, bills, receipts, invoices etc. It is listed one by one. Copy Circulation: It is needed when the copies of the letter are sent to other persons. It is denoted as C.C. PostScript: The sender can mention it when he wants to add something other than the message in the body of the letter. It is written as P.S.
How do you know for sure whether or not to use a closing? One good test is to ask yourself whether this email is more akin to an instant message/text or a business letter. If you're giving your teammate a quick update on an ongoing project, a formal closing might not be necessary; if you're throwing your hat in the ring for a promotion, it definitely is required. When all else fails, and you're still not sure, err on the side of caution and include it. You'll never go wrong by being too polite and respectful.