warren@ihnss.UUCP (09/20/83)
Is there a standard way to distinguish mail sent from automatic sources, such as vacation mail processors, mail daemon processes that return undeliverable mail, etc., from human generated mail? I ask this after some recent discussion on the problems of writing a mail handler that replies for you while you are on vacation. Such a handler should ideally not reply to anything that is mechanically generated (such as another copy of itself, or a mail item returned from some other source), or looping may result. (There is a probably somewhat appocryphal story about the first vacation mail handler at MIT, which supposedly took down the Arpanet when two of them got into a duel forwarding messages at eachother). My purpose would equally well be served by a header field tagging sources that should not be sent mail. If a standard convention for either of these, I would like to use it. If not, I think that it is a reasonable idea to adopt one. -- Warren Montgomery ihnss!warren IH x2494
ka@spanky.UUCP (Kenneth Almquist) (09/20/83)
A simple way for vacation mail processors to avoid infinite loops is for them to only reply to the first letter from any given address. Kenneth Almquist
rld@pyuxnn.UUCP (Bob Duncanson) (09/20/83)
I urge you to write a Program that could read messages and decide whether
it was tlaking to a Person or to a Computer.
Then we could leave Turing's test to an impartial machine to decide.
>>>>> Bob Duncanson, AT&T Bell Laboratories, eagle!pyuxnn!rld <<<<<smb@achilles.UUCP (Steven Bellovin) (09/20/83)
The story about mail loops is not at all apocryphal (though it may not have crashed the ARPAnet); I can dig up references if anyone wants. But I know it can happen, because it did happen at UNC with a vacation reply system I wrote.... Fortunately, mine was clock-triggered, so it didn't send more than one message per hour. Yes, as spanky!ka says, a vacation processor that sort should keep a list, but that doesn't answer the more general question. My processor excluded mail from 'root', 'daemon', 'uucp', and a few other logins. Other possibilities include using the 'From' line to indicate the program, and the 'Sender' to indicate who's responsible for it; RFC822 seems to bless such an interpretation. --Steve Bellovin
thomas@utah-gr.UUCP (Spencer W. Thomas) (09/21/83)
Not only should "vacation" programs not reply to messages from other such programs, but they should also never reply to messages on a mailing list. The classic example here is (on the Arpanet) unix-emacs@cmu-cs-c which mungs the headers so the return address is (guess what...) the whole list! I've only seen one "I'm on vacation..." message on it so far, but that's probably due to the scarcity of vacation programs. =Spencer
CSvax:cak@pur-ee.UUCP (Christopher A Kent) (09/22/83)
The way I handled mailing lists in my vacation answering machine was to be sure that the To: line had "cak" in it. Cheers, chris (cak) kent