My 4-year-old list is set up to probe every six months. Yet, none of the other Listserv lists I belong to ever probes me. Some of them are x times larger than my list. I would like to remove it from my header, if possible. From a practical sense, is it necessary to probe a subscriber who gets no mail? It adds to the error messages and monitoring report along with all of those "unknown" names there already. It is an extra burden I would like to dispense with. If it is not recommended, what is the longest time that can be reasonably set for probing? I am presently set for 6 months. Barbara Passmore