A system/method for preventing a computer virus from accessing message addresses is described. The system comprises an interception component or client plug-in that communicates with a messaging client and a messaging server. The interception component alters messages from the server and destined for the client. The interception component replaces message addresses in incoming messages with a unique identifier. The interception component also alters messages from the client destined for the server. The interception component replaces a unique identifier with a message addresses. A system/method for preventing keyboard sniffer programs from intercepting input, a system for preventing a computer virus from activating a send confirmation of a messaging client and a method for altering displayed objects to show encrypted data in decrypted form are also described and claimed. A system/method for reducing the impact of keyboard sniffer programs by altering keyboard input.