How is the lockbox file different from the electronic bank statement file?
The lockbox file contains the remittance information the customers have sent to the bank, for example amount and number by invoice. That level of payment information allows easy reconciliation and clearing of open items in SAP Accounts Receivable. It is normally used for check payments only.
Within the electronic bank statement file you can have various types of payment transactions. The remittance information in the electronic bank statement file is limited and provides you with the consolidated amount paid by the customer. It is possible to use only one of these services, or both in combination, depending on the company’s needs. When using lockbox and electronic bank statement it is important to set up the posting rules in SAP correctly to avoid incorrect postings. The main lockbox program will debit the bank clearing account for accounts receivables and post a credit entry to the bank clearing account for incoming checks (lockbox). In a second posting area, the program will debit the bank clearing account for incoming checks and clear open items in the customer accounts. The remaining open items on the bank clearing account for accounts receivables will be cleared through the electronic bank statement. The electronic bank statement will debit the main bank account and credit the bank clearing account for accounts receivable.
Excerpt from Electronic Bank Statement & Lockbox in SAP ERP by Lennart Ullmann and Claus Wild.