Collection letters, therefore, should be persuasive rather than forceful, firm rather than demanding. A fair and tactful letter gets better results than a sarcastic or abusive one. In fact, even collection letters should be 'you-oriented": courteous, considerate, and concerned about the customer's best interest. Collection letters are usually sent in a series. The first tends to be mildest and most understanding, with the letters getting gradually more insistent. The final letter in a series, when all else has failed, threatens to turn the matter over to a lawyer or collection agency. Of course, the tone of any letter in the series will vary, from positive and mild to negative and strong, depending upon the past payment record of the particular customer. The intervals between the letters may also vary, from ten days to month at the start, from one to two weeks later on. Every letter in a collection series should contain certain information: 1) the amount owed; 2) how long the bill is overdue; 3) a specific action the customer may take. Some companies also like to include a SALES APPEAL, even late in the series, as an extra incentive for payment.