If you attach something to an email, it is usually a good practice to include at least a line in the body of the email telling the recipient what you’ve attached. For example, suppose an employee in a company’s billing department emails an invoice to a client, but doesn’t identify the attachment or include any text in the email body. The recipient may think it is a virus and delete the email without ever opening the attachment.
Or, suppose you email a request for a file on a Wednesday, and the recipient doesn’t reply with the attachment until Friday. Aside from the tardiness of the response — potentially problematic in itself — the person includes no explanatory comment of any type in the body of the message; he simply attaches the requested document. By this point, you may well no longer remember that you requested something from the recipient. The writer should therefore clarify the purpose of the email and identify what is attached to it. Usually, though not in every case, information about the attachment should appear in the very first lines of the message. See Section 5.2.2 for recommendations on how to word such sentences.
Before you send an attachment, double-check that you have attached the right file. Open it just to be sure.