Employers rarely expect references from a candidate's current employer. They understand the need for confidentiality. Although they might check on your present responsibilities and performance through their network of contacts, you will rarely be required to provide official references from your current employer. If you must provide a confidential reference, however, select a friendly supplier, client, peer, ex-employee, or consultant familiar with your work. Never select a reference source that is in a position to retaliate or interfere with your present employment if your new job doesn't materialize.
Credible references can make all the difference in the final stages of the interview process.
Ministers and relatives are regarded as poor references because employers assume they are biased in your favor. Send mail first class or express. Express mail may be an even better choice to encourage immediate, positive consideration. Use a folder that allows you to keep your papers flat, and include a stiffener so they arrive unwrinkled. Don't fold them into a letter-sized envelope.