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Re: OP mail delayed?

From: Bob Proulx
Subject: Re: OP mail delayed?
Date: Fri, 13 Jun 2008 10:58:39 -0600
User-agent: Mutt/1.5.13 (2006-08-11)

I am not a subscriber of help-gnu-emacs.  Please CC me on replies.  I
am one of the listhelpers that tries to keep spam off of the mailing
lists and do other list maintenance.  I happened to see this
discussion about delayed email delivery and wanted to say a few words
about it.

Drew Adams wrote:
> . Others are seeing the same thing.

There are several reasons this might occur.  One is when there are
several discussion groups for help-gnu-emacs.  I don't know about
help-gnu-emacs in particular but some mailing lists are gatewayed
between an email mailing list and a usenet news group.  Personally I
think that is a bad idea because the mailing list and the newsgroup
have a different set of posting rules.  But in that case an OP who is
not subscribed nor whitelisted may post a message to the newsgroup.
Another person who is subscribed or whitelisted in the mailing list
might see a newsgroup posting from a new address and respond to it on
the newsgroup.  Then both messages are gatewayed to the mailing list.
Because the responder is known to the mailing list it is passed
through without delay.  Because the OP is unknown to the mailing list
the message must be approved by a human until the address proves
itself not to be a spammer and becomes known.

One of the problems of gateways are that a spammer posts spam to the
newsgroup and everyone on the news group will see it.  People then
sometimes respond to the spam.  When the messages are gatewayed to the
mailing list the spam filtering will discard the original spam
message.  Mailing list readers won't see the spam.  But responses to
the spam message by whitelisted posters are not discarded and
therefore readers of the mailing list will see spam coming from the
newsgroup by way of newsgroup responses but will never have seen the
original spam.  Because of the newsgroup response it can pull spam
through from the newsgroup onto the mailing list.  If spam is
cancelled from the newsgroup later this can't cancel the spam message
already delivered to the mailing list.

> . This just started happening - it didn't happen before.

If this really just started happening then this probably isn't a
mailing list to news gateway issue.  Unless a new newsgroup has popped
up recently most of these have been pretty stable for a long time
(years) and you would have been seeing this all along.  Therefore
recent behavior changes would probably indicate something on the
client end of the email delivery.

> . I don't see this in other GNU Emacs mailing lists.

All of the mailing lists are handled similarly.
Therefore once again this points to something on the client delivery

> What is the difference between a message with RE coming from the list and a
> message without RE? Wouldn't they both be treated the same by a spam
> filter? Why would the latter (the OP) be delayed more than the
> former?

Messages from addresses unknown to the system, not subscribed and not
whitelisted, are held for approval until one of the human listhelpers
can review the message and send it on its way.  The address is added
to the subscription whitelist and subsequent messages are passed
through without delay.  This step is needed because spammers are now
routinely attacking by subscribing and then posting spam
from subscribed addresses.

On your client system if greylisting is implemented (possibly
incorrectly) then your client system will reject temporarily based
upon configured parameters of host system and email addresses in the
sender and recipient fields.  Normally the mailing list would generate
enough continuous traffic that the host machine would be
in the known okay host list all of the time and mail from it would
never be delayed.  But it is possible that an overly agressive program
may be written that looks at the original sender and delay mail based
upon the sender address and not the sending host.  This would delay OP
mail from new addresses from the mailing list but would send directly
through response mail from frequent responders.  This would cause
exactly the situation that you describe.

I use greylisting myself and the well known greylisting daemons behave
reasonably by default in this regard and should not create this
problem.  But I think an incorrectly constructed process could easily
create this problem.  If your email delivery has recently gotten more
agressive at spam filtering then something along these lines may be

And of course the problem you are seeing might be for any one of a
number of other reasons too.

> This is not about messages sent directly to me from someone. It is about
> messages that come from this list.

If you contact me off-list with message-ids of messages that fall into
this catagory I can chase down more details.


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