Dunning letters are usually sent through express delivery stations. When the borrower fails to repay the loan within the time limit, the online lending institution will send a collection letter to remind the borrower to repay the loan in time. In order to ensure that the dunning letter can be delivered to the borrower accurately, the online lending institution needs to first determine the detailed address of the borrower and send the dunning letter by mail or express delivery. When filling in the delivery document, you need to provide the delivery address, recipient name and other information. Whether by mail or express delivery, you need to keep the corresponding delivery voucher. A collection note is a collection tool, which is usually issued by a collection agency designated by creditors or debtors. Its main purpose is to ask the debtor to repay the arrears of debts or overdue funds. The dunning letter will include the debtor's personal information, details of the debt, overdue time and action to be taken. The collection letter does not mean being sued, but a means of collection adopted by creditors.