On Sat, 13 Feb 1993 13:41:18 -0500, Joan Korenman <Korenman@UMBC2> wrote:
> There is a subscriber on my list whose
> e-mail domain is recorded as @helios.uwc.edu.  But most of the mail sent to
> her from the list bounces, with an error message like the following:
>> Date: Sat, 13 Feb 93 02:09:56 EST
>> From: <[log in to unmask]>
>> Subject: Undeliverable Mail
>>
>> pucc.PRINCETON.EDU unable to deliver following mail to recipient(s):
>>    <[log in to unmask]>
>> 550 Host 'HELIOS.UWC.EDU' Unknown
>
> I've deleted her twice, most recently today.
> But almost as soon as I deleted her, she resubscribed.
 
Hmm.  How did Linda know that you had deleted her?
Two possibilities:
 - Linda didn't get the response from LISTSERV, so she just tried again.
 - you used 'DELETE listname user@node' rather than 'QUIET DELETE ...',
   and the "non-quiet" command sent notification to Linda that you had
   removed her.  If Linda **did** receive the notification, she could have
   reacted, by repeating her subscribe request.
 
> I then tried to write to her to explain why I deleted her and to ask her to
> talk to the computer support people at her institution, but my message to her
> (sent from a system different from that of my list) also bounced for similar
> reasons.
 
In the first case, it was the SMTP-server at PUCC which couldn't deliver
E-mail to her.  When you tried to send E-mail to her, it (probably) was
your local(!) SMTP-server which couldn't deliver E-mail to her.
Take the fact that two different servers couldn't deliver the mail
as a hint that something is wrong at the "far" end, or somewhere along
the path to the "far" end, rather than a hint that there's a problem
**both** at PUCC and at UMBC2.
 
When I query the Internet name-servers, I find that the host 'HELIOS.UWC.EDU'
has an IP-address of 143.235.1.12, and the name-servers running on the hosts
named 'UWCMAIL.UWC.EDU' and 'DOGIE.MACC.WISC.EDU' are listed as the
"authoritative" name-servers for the 'UWC.EDU' domain.  If I explicitly
ask the 'UWCMAIL' host for the IP-address of 'HELIOS', it returns the
correct result.  If I explicitly ask the 'DOGIE' name-server, it returns
a "non-existent domain" error-message.  Huh?  Strange!  So, in this case,
depending on which name-server you ask, you obtain different answers!
 
I suspect that the name-server system on 'DOGIE' is "sick", i.e., misbehaving,
or that the IP-addresses for all the hosts within the 'UWC.EDU' domain
have not been loaded into this name-server.  Thus, although 'DOGIE'
is listed as being "authoritative" for the 'UWC.EDU' domain, it has no
information stored, so, all queries can only return a result of "unknown".
 
I'm sending a copy of this E-mail to [log in to unmask],
which is the ID of the person(s) responsible for the name-servers within the
'WISC.EDU' domain.  Hopefully, they'll investigate the behaviour of 'DOGIE'.
(Bad-joke: should we ask Doogie Howser to consult on DOGIE's illness?)
 
Also, when I enter 'PING 143.235.1.12', it **does** respond.
Thus, the machine at that IP-address is "alive".
 
Also, when I enter 'TELNET 143.235.1.12', it responds:
   UNIX System V Release 4.0 Version 3.0 (helios)
That's more proof that the machine is "alive".
 
> Also, is there a way to delete someone so that they can't resubscribe?
No, "list-owners" don't have that privilege -- only "listserv-managers" can.
 
However, you could do a 'QUIET SET WMST-L NOMAIL FOR [log in to unmask]
She would then be "subscribed", but LISTSERV won't send any E-mail to her. :-(
Thus, no "bounce" messages would be generated.  :-)