Date: Wed, 22 Nov 1995 16:28:00 -0500 (EST)
From: malgosia askanas <ma-AT-panix.com>
Subject: Mail loops -- PLEASE READ



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Dear All,

There have recently been some very unpleasant mail-loops occurring on
first heidegger and then postcolonial-info, so I would like to tell you
a bit about what to do in such cases.

In my experience, there are two kinds of mail loops.  One occurs when
there is some error in delivering mail to a subscriber, and the subscriber's
system is misconfigured do that the error message goes not to the list
owner (spoons), but to the list itself.  Since the subscriber is _on_ the
list, the error message also goes to hir, causing another error message,
which also goes to hir, causing yet another error message, and so on.
These kinds of loops usually have the property that each subsequent message
includes the preceding one, and thus the messages get longer and longer.
At the same time, these loops, once caught, are easy to deal with: the
Spoons can deal with them by unsubbing the person whose system is sending 
them, and each of you can deal with them by temporarily unsubbing from
the list and then resubbing after a day or so.

The other kind, which is what we've had on heidegger and postco-info, is
different.  What happens there is that for some reason (unknown to
everybody I've talked to) a message gets stuck on the outgoing mail
queue of the Virginia computer and, instead of being removed after
having been sent, gets sent out again and again.  This problem cannot
be dealt with by unsubbing anybody, because the list of addresses is
already attached to the stuck message -- the message keeps getting sent 
to the same list of addresses, irrespective of the changes in the
subscribership of the given list.  The only way to solve this kind of
problem is to remove the offending message from the mail queue, which
currently requires the intervention of the Virginia sysadmin, and thus
can take a while (especially on weekends).

So here are some guidelines for dealing with these situations:

- _Never_ react to mail loops by sending a message to the list itself.
  Your message can cause another loop and aggravate the problem.
  Send a message alerting us to the loop to 
  spoons-AT-jefferson.village.virginia.edu.  Such an alert is especially
  invaluable in the case of the second kind of loop, because those have
  the property that the looping message is not sent to _all_ subscribers,
  but only to some misterious subset, so that we may not even be aware
  of the problem.  

- In the case of the first kind of loop, the best course of action is
  to unsub from the list and then resub after a day or so.

- In the case of the second kind, there is unfortunately nothing you
  can do to protect yourself from the influx.  Send a message to spoons
  and then bear with us as we alert the Virginia sysadmin to the problem.
  We realize that these loops are catastrophic to your mailboxes, and
  try to act as quickly as possible.  


Yours,

-malgosia askanas, for the spoon collective