An electronic commerce system provides various features for assisting customers in locating items and generating orders from a merchant's electronic catalog, and for assisting customers and merchants in communicating about such orders. A user-definable categories feature allows customers and/or merchants to define search queries for searching the electronic catalog, and to store these search queries under user-defined category names for subsequent use. An “active quote” feature allows the customer to view and modify quantities of items selected for prospective purchase throughout various catalog browsing or viewing modes. A message audit trail feature allows a customer and a merchant to send messages to one another that are linked to a particular order, and to view an order-specific log of such messages.