1234, Main Street
Boston, MA 02123
04 April, 2005
<Recipient Address Goes Here>
Re: Account No. <account number>
Please be advised that the above-referenced account is now <number of days> days past due. Despite repeated requests for payment, we have not heard from you or received payment. Accordingly, unless we hear from you or receive payment of <$amount> within <number of days> days from the date of this notice, we will be forced to turn this account over to a collection agency.
Please protect your credit rating and avoid the unpleasantness of dealing with a collection agency by mailing your payment or contacting us today.
Thank you for your immediate attention to this request.
encl: <List of enclosed items goes here>