When you use OOM under .NET, your using managed code around COM objects via the Outlook Primary Interop Assembly (PIA). When you have managed code working with COM in this way, you have to be very careful to clean-up your references. .NET will hold onto COM objects, sometimes causing leaks, and sometimes reusing them (called COM Ressurection). This leaks… void onEvent_ItemSend( object Item, ref bool Cancel ) { try { MessageBox.Show( "Application ItemSend Event Fired." , "onEvent_ItemSend" ); } catch