From: jim@ferkel.ucsb.edu (Jim Lick)
Subject: Re: Full mail spool policy?
Organization: University of California, Santa Barbara
Date: Thu, 19 Nov 1992 00:51:20 GMT

In <BxwzoA.325@gabriel.keele.ac.uk> cca09@keele.ac.uk (Norman Bridges) writes:
>That's getting a real problem here too. I feel that a responsible
>automatic mail server should be auditing its readership once in a
>while and asking readers to specifically re-subscribe.

Sorry, but that's just not going to happen.  Even with an automated
system, this is going to create a collosal headache for the admin
and the subscribers.

>                                                        I also feel
>that not enough is done to give sysadmins facilities to unsubscribe to
>mailing lists on behalf of dead accounts. [My apologies if such
>facilities do exist, its just that it can be difficult to locate the
>address for unsubscription without prying into a user's mailbox].

The usual mechanism is to remove the account.  Most decent lists will
have bounces directed to an admin address.  Others will bounce to the
poster.  Sometimes the poster will forward these to the admin.  Otherwise
the list admin will post a message periodically to catch bounces.

Apropos to the original subject, many lists employ a system where mail
to a user bounces if their mail file is over some limit.  Some mail
systems (Sendmail+IDA for example) allow you to setup customized
per user bounce messages.  Examples include "joeuser has not logged
in in over 2 weeks; mail rejected" or "joeuser account has been
disabled; mail rejected".  

I've received mail from some admins asking to please remove so-and-so 
from your list, so obviously some admins will go through the users mail 
file.  I don't particularly like this approach though, as it may be in
violation of the user's privacy.  I would recommend the following
approaches to these problems:

Problem: users often have multi-megabyte mail spool files, and the
spool area is in danger of filling up.

Solution: Impose a mail spool size limit.  When a user reaches the
limit, mail the user a note along the lines of "Your incoming mail
file has exceeded out xxxKB limit.  Incoming mail will be disabled
until you trim your file to less than this limit." then bounce all
additional mail to that user back with the message "joeuser has
exceeded the local mail file size limit." until the file size shrinks.

Problem: users subscribe to mailing lists but then don't log in for
several weeks.

Solution: If you are only concerned with the file sizes, the above
size limit should be sufficient.  If user en abstentia is your main
problem, you could start bouncing mail if a user hasn't logged in in
a while.  This especially seems to be a problem over the summer
vacation.

Problem: user's account has been removed or disabled

Solution: It is usually sufficient to just delete the account.  However,
no such user bounces don't always mean that the user is gone.  Sometimes
it means oops our NIS just broke or oops our system is going bonkers.
ocf.berkeley.edu is notorious for periodically bouncing mail with the
'no such user' message when really it was just having a bad day.  I'll
usually allow bounces to continue for a few days in case the problem
was temporary, but if it was bounced back with the specific message that
the user no longer has an active account, then I'd delete the address
immediately.

The advantages of these systems is that once they are set up, if your
software allows it, then everything is basically on auto-pilot.  You
also don't have to rifle through private files either.

--- jim@ferkel.ucsb.edu --- Jim Lick --- jim@tcp.com --- jIngOrO@CaveMUCK ---
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