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 past due. Your payment of <$amount> was due on <date>. To date, this amount has not yet been received. If payment has recently been made, please accept our thanks and disregard this notice. If payment has not yet been made, however, please take a moment now to send your payment and prevent this account from becoming delinquent.
Thank you for your prompt attention to this reminder.
encl: <List of enclosed items goes here>