Some of the list keywords are documented in LISTKEYW MEMO available
from Listserv. The following is a description of loopcheck, obtained
and edited from archives of LSTSRV-L.
(...) LISTSERV looks into the body of the mail, in an attempt to
recognize mail that may be looping between a LISTSERV list and a
foreign mailer. Quite a few checks were put in as part of 1.5l, but
they don't apply to your 1.5i system. The only pre-1.5l checks I can
recall are that the body must not contain either:
1) "From: <list>";
or 2) "Sender: <list>"
where <list> contains: ({x} means "x is optional")
1) {"<"}<listname>"@"<listnode>{">"};
2) {"<"}<listnode>"!"<listname>{">"} (for UUCP bigots);
or 3) {"<"}<listname>"%"<listnode>{">"}.
Perhaps you might find an incentive to upgrade to 1.5l in the fact
that it offers a new list keyword, "LoopCheck = {Full / NoBody /
NoToCount}, MAXTO(nnn)". With LoopCheck=NoBody, the above checks are
suppressed.
Ross Patterson
Rutgers University
default
LOOPCHECK: 'FULL'
The "Loopcheck=" keyword was implemented because a number of people were
requesting it so aggressively that I decided it would be better to spend
10 minutes implementing it than hours answering their endless downpour of
arguments, plus they were making local changes to turn it off on their
server anyway - with the side-effect that lists where they did not want
it turned off were also affected. Anyway to re-enable loop checking all
you have to do is remove the keyword.
Eric
>>> Item number 3023, dated 90/09/10 00:56:58 -- ALL
Date: Mon, 10 Sep 90 00:56:58 O
Reply-To: "Forum on LISTSERV release 1.6" <[log in to unmask]>
Sender: "Forum on LISTSERV release 1.6" <[log in to unmask]>
From: Eric Thomas <[log in to unmask]>
Subject: Re: loopcheck
In-Reply-To: Your message of Sun, 9 Sep 90 18:26:45 EDT
The best value for "Loopcheck=" is no value, ie edit the list header and
remove the string "Loopcheck= Nobody". Any other value apart from "Full",
which is the default, means that some or all of the loop checking
routines are disabled. "Nobody" means that LISTSERV is not allowed to
look into the message body to decide whether or not something is a
delivery error; it is to rely solely on the 'Subject:' field. As you can
imagine, this is a very dangerous option: it means that any mailer not
using one of the "standard" subjects known to LISTSERV will cause a loop.
"None" is even worse, it tells LISTSERV that, by definition, anything
that reaches its reader is NOT a delivery error. These two options should
never be used unless the list is moderated. Even if the list is moderated
they are not recommended, especially if the moderator is not the list
owner (ie administrator). I actually regret having implemented these
options, it really scares me to think that people are using them without
knowing what they do.
"Notocount" means that LISTSERV should not count the 'To:' fields in the
message body and decide it is seeing a delivery notice if there are too
many; "MaxTo(nnn)" orders it to allow up to the specified amount of 'To:'
fields, the default is 10. This is the one sub-option of the "Loopcheck"
keyword that can be useful - for digests. The code that counts the 'To:'
field is here as a kind of "last resort" action anyway, to prevent
infinite loops, but it won't stop the redistribution of the first 'nnn'
nastygrams. If you disable this routine it means loops can become
infinite, but it doesn't have any effect on the actual detection of new
loops.
Finally, the latest addition, "NoCRC", means you don't want to suppress
duplicate messages on the list, ie if RSCS at FOO becomes crazy and sends
you 200 copies of the same posting, as it happened for LSTSRV-L, INFO-VAX
and many other lists about 6 weeks ago, you will happily redistribute the
200 copies. I added this option as a kind of "emergency bypass" in case
the new code that detects such duplicates should break and start
rejecting all postings. Fortunately this did not happen, so you can
forget about it.
Eric
>>> Item number 4057, dated 91/10/10 10:53:43 -- ALL
From: Greg Kroll <[log in to unmask]>
> LOOPCHECK: (default value FULL)
This controls which of the loop-detecting heuristics are used for this
list. Sorry, I don't have time to compile a complete list of options.
The important ones are FULL and NONE, with meanings that should be
obvious.
>>> Item number 4180, dated 91/11/25 06:20:19 -- ALL
From: Eric Thomas <[log in to unmask]>
Subject: Changes from release 1.7a to 1.7b
New New loop-detector option, "Loopcheck= NoOrigin", permits the
list owner to disable the check for "known mailer origins"
such as MAILER, POSTMASTER, ROOT, UUCP, et al. Mail whose
'From:' field is the address of the local mailer is still
trapped, but wildcard checks on the mail origin are disabled.
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