Mon, 13 Jul 2009 06:00:11 This message is a "probe" for your subscription to the IBM-MAIN list. You do not need to take any action to remain subscribed to the list, and in particular you should not reply to this message. Simply discard it now, or read on if you would like to know more about how this probing mechanism works.
A "probe" is a message like the one you are reading, sent to an individual subscriber and tagged with a special signature to uniquely identify this particular subscriber (you may not see the signature because it is in the mail headers). If the subscriber's e-mail address is no longer valid, then the message will be returned to LISTSERV and the faulty address will be removed from the list. If the subscriber's address is still valid, then the message will not bounce and the user will not be deleted. The main advantage of this technique is that it can be fully automated; the list owner does not need to read a single delivery error. For a large or active list, the manpower savings can be tremendous. In fact, some lists are so large that it is virtually impossible to process delivery errors manually. Another advantage is that the special, unique signatures make it possible to accurately process delivery errors that are otherwise unintelligible, even to an experienced technical person. The drawback, however, is that this method lacks flexibility and forgiveness. Since the Internet does not provide a reliable mechanism for probing an e-mail address without actually delivering a message to the human recipient, the subscribers need to be inconvenienced with yet another "junk message." And, unlike a human list owner, LISTSERV follows a number of simple rules in determining when and whether to terminate a subscription. In particular, a common problem with automatic probes is mail gateways that return a delivery error, but do deliver the message anyway. LISTSERV has no way to know that the message was in fact delivered, and in most cases the subscriber is not aware of the existence of these "false" error reports. If this happens to you, LISTSERV will send you another message with a copy of the delivery error returned by your mail system, so that you can show it to your technical people.
