Brian K. Fistler on tue 16 may 06
On Mon, 2006-05-15 at 16:14 -0500, mel jacobson wrote:
> we have a great many folks out there in
> clayart land that are having problems getting
> clayart through your isp.
>
> it is an on going problem...some of you have
> addressed it with help.
>
> i just went through it. super/duper/huge/spam filter
> system applied without my knowledge. it grabbed
> every clayart post and dumped it.
> almost 1400 spams and posts all gone.
>
The problem is that many spam filters utilize what are called "DNS
Blacklists" as one, or some times their only, of the tests to determine
if a message is spam or not. These black lists only record the IP
address of the sending email server, and if a spam has been reported
from one of those IP addresses, it gets marked as spam.
Looking through a few of the recent messages, I see that the
btopenworld.com server that May's message was delivered through is
listed in the sorbs.net dnsbl server.
( http://www.dnsbl.sorbs.net/cgi-bin/lookup?IP=217.12.12.38 )
(It's not May's fault... it's May's ISP's fault, btopenworld.com, for
allowing themselves to get listed by not shutting down spammer's and/or
locking out users that have viruses that are spamming.) Black-Lists will
almost ALWAYS send an email to the ISP's "abuse@xxx.xxx" email address,
but many ISP's either don't have this email address properly configured,
don't monitor it, or just ignore the warnings that they are blocked and
do nothing to clean up the spammers on their networks, so stay listed.
Those people sending email from yahoo email accounts can also get
blocked, but often it is a more random nature, as Yahoo has thousands of
email servers, many of which are blocked at any given moment, which
server your message is sent through, and wether or not it is in some
black-list is just a matter of chance. (Actually, it looks like
btopenworld.com that May uses is actually delivering email through
yahoo...)
If someone's ISP (Internet Service Provider) is using dnsbl.sorbs.net as
a "front-line" blocking list, May's email would not have gotten to that
person.
Also, because this listserv keeps the meassage headers intact, when a
black-list is queried by the receiving mail server, the IP address that
is checked could be the IP address of the listserve, as well as the IP
address of where the message originated (in this case btopenworld)
There are dozens of different black-lists that can be checked by the
receiving mail server, some of these black-lists are much better at
others, and it will all depend on which black-lists are being queried by
the receiving person's ISP. (sorbs happens to be quite popular, as well
as quite accurate.)
Unfortunately, the black-list way of blocking spam is the easiest for
Internet Service Providers to implement, but it doesn't actually look at
each message to determine if it is spam or not.
Some service providers implement this system-wide because it reduces the
number of spam messages it has to process, allowing them to continue
using the email servers they already have in place in the face of
increasing spam. Filteirng that implements other methods that look at
the individual messages rather than the black-lists take much much more
processing power and could require thousands of dollars of investment in
hardware.
NOT blocking spam is also not an option for many of these ISP's as the
increased load placed on the servers by the incredible amount of spam
circulating would also force many to upgrade equipment well before they
would if there were no spam.
It is estimated that approximately 60-70% of all email that is processed
by a mail server is spam, so you can see what a problem this is for
internet providers.
The best solution, of course, would be to get off of yahoo groups, but
that causes lots of other headaches for our moderator.
For those users who have the problem of their ISP blocking emails, they
can try contacting their ISP to see if they can "white list" this group.
It's worth a try anyway... If you do try to get your ISP to whitelist
this group, tell them that the IP address the messages are coming from
is 209.115.31.62. The entire 209.115.31.32/27 is registered to
ceramics.org, but it looks like the listserve is only utilizing hte
209.115.31.62 address.
If you have a smaller (responsive) ISP and you give them the ip address
to white-list, you might just have good luck getting them to add that
209.115.31.62 ip address to a whitelist file. If you are using a larger
ISP, I wish you good-luck! :) (If properly white-listed, when the
receiving mail server sees that it is 209.115.31.62 connecting to
deliver the message, the server will trust what is it delivering,
bypassing the rest of the checks, so the originating IP address, in this
case May's would never be checked.
Brian
May Luk on wed 17 may 06
Hello Brian;
I can confirm that BTopenworld (British Telecom AKA BT
Yahoo) is affiliated with Yahoo. Like most (big)
British companies, they are rubbish in services. They
are also clueless with Mac's.
Oops, did I say that?
Thanks for the explanation.
May
LondON, UK
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