Using email plus Excel for transaction documents typically creates three types of problems. First is version confusion—once both buyer and seller make edits, it becomes hard to confirm "which version is currently in effect," especially after a quotation has been modified several times. Second is scattered information—inquiries in your inbox, quotations in Excel, payment terms on LINE. If anything goes wrong, tracing back requires digging through multiple places. Third is handoff difficulty—when a salesperson leaves or takes time off, their replacement essentially has to start from scratch to take over an order. Centralizing transaction documents in a single system, where each sent version is automatically retained, changes by both parties can be compared column by column, and communication records are linked to their corresponding documents is the baseline approach to reducing these risks. This isn't just an efficiency issue; it directly affects your ability to handle disputes after shipment.