rem: destUri = destFolder.getAttribute('id'); destResource = RDF.GetResource(destUri); destMsgFolder = destResource.QueryInterface(Components.interfaces.nsIMsgFolder); 
add: var destUri = destFolder.getAttribute('id'); var destResource = RDF.GetResource(destUri); var destMsgFolder = destResource.QueryInterface(Components.interfaces.nsIMsgFolder); 
context: function MsgCopyMessage(destFolder){    // Get the id for the folder we're copying into    destUri = destFolder.getAttribute('id');    destResource = RDF.GetResource(destUri);    destMsgFolder = destResource.QueryInterface(Components.interfaces.nsIMsgFolder);    var srcFolder = GetLoadedMsgFolder();    if(srcFolder)    {        var compositeDataSource = GetCompositeDataSource("Copy");        var messages = GetSelectedMessages();        CopyMessages(compositeDataSource, srcFolder, destMsgFolder, messages, false);    }    }
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