Rob F's vm-avirtual package (section 13.4 of the manual) has an operation that can be used to "update" virtual folders for a particular message. Invoking it by hand every time would be tedious. But there might be a way to add it as an advice for the add-label function. I haven't explored that idea.
Rob F's vm-avirtual package (section 13.4 of the manual) has an operation that can be used to "update" virtual folders for a particular message. Invoking it by hand every time would be tedious. But there might be a way to add it as an advice for the add-label function. I haven't explored that idea.