SPAM on List...
John E. Malmberg
wb8tyw at qsl.net
Fri Nov 15 02:08:00 EST 2002
Re: Per the discussions about spam on this list.
Sending a confirming message to an unregistered poster is not a good
idea. The return/reply-to addresses in spam is forged, and that is just
adding to some victims e-mail.
Filtering runs the risk that a legitimate message gets lost, and the
sender does not realize it.
Filtering is also the most expensive and innefficient way to deal with
spam, if you control the e-mail server.
It is kinder to the senders (even though some may not appreciate it) to
use one or more DNS based blocking lists to keep the spam down.
That way the sender gets notified that there is a spam problem with the
server or domain that they are sending from, and they can either put
pressure on their ISP to fix it, or if it turns out that the ISP values
the spammers money more than their other customers, they can find
Many e-mail servers are now using DNS based blocking list. They are
blocking open-relays, open-proxies, Known Dialup ranges, and address
blocks that have sent a high volume of spam.
The SAMBA-TECHNICAL list reported that they have gone to the
bl.spamcop.net blocking list, and it has been relatively spam free since
then. The bl.spamcop.net is an aggressive blocking list with a quick
And there are spamcop members on that list that send feeback to spamcop
that if a spammer shows up, only one or two spams will show up from that
It takes a few spam requests to trigger a block, and there is a penalty
for false or malicious reports. Reports are only accepted from
registered spamcop members. There is no charge for registering.
Most of the blocking lists on the Internet take a long time for the
sending I.P or block to get off.
The spamcop blocking list entries expire in as short as 3 hours from the
last reported spam. If the ISP shows up on spam reports chronically, it
then can take up to one week for the last reported spam to get de-listed.
This makes the bl.spamcop.net good for a mailing list. If the e-mail is
bounced with the code for try-again, instead of permantently fatal, and
the sender is on an ISP that responds to spam complaints, the e-mail
would probably get posted that day. If the sender's ISP is not
responding to spam complaints, it is likely that the sender is not
having much luck getting anyone to accept their e-mail.
QSL.NET also appears to use the spamcop blocking list. They are doing
it because spam last year was costing them $30% of their internet costs.
While most of you may pay a fixed rate for your e-mail, an ISP or a
large company have to pay based on the amount of data transfered.
With e-mail, a postmaster do not know how much the e-mail is going to
cost until the server has accepted it. And the only thing that a mail
server knows before accepting an e-mail is the sending server's I.P.
A typical e-mail is under 5k bytes in size, some of the spam coming
through is well over 50K bytes.
So economically it is in the best interest of a postmaster to use
blocking lists. It is up to the postmaster to determine how strict of
ones to use.
And many companies/postmasters do the blocking on a second level server,
so the spam (and any thing that is mistaken for spam) is simply black holed.
So bouncing a message because it comes from a server or I.P. block
infested with a spammer may give someone a clue as to why they are not
getting responses from their e-mail.
Also many of the companies/ISPs that are blackholing spam will not admit
to it because they do not want to be accused of censorship. So when
someone complains to the ISP that an e-mail from a specific address not
being received, they say that they can not find anything wrong and
suggest that it be sent again. And magically things start working with
that address, as long as the spam that caused it to be blocked in the
first place does not start up again.
The internet is dividing into ISPs and postmasters that tolerate spam
and those that do not. And boycotting the ISPs that allow spam to be
sent has been shown to be the only thing that is effective in reducing spam.
wb8tyw at qsl.network
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