To modify outgoing chat messages we are going to hook the ChatEdit_ParseText function. However, this function also handles macros; so to avoid tainting we must use hooksecurefunc() to hook the function properly. Otherwise, your macros will no longer work. -- Place this code in the OnLoad function of your addon hooksecurefunc('ChatEdit_ParseText',MyAddon_ParseText); MyAddon_ParseText will now be called after ChatEdit_ParseText has had a chance to handle macros and slash commands.