[Spambayes] Beyond Spambayes
wsy at merl.com
Thu Feb 23 00:56:51 CET 2006
From: "Seth Goodman" <sethg at GoodmanAssociates.com>
For the oddball dynamic IP from which you need to receive messages, add
them to a whitelist.
Therein lies the problem; a dynamic IP can't be whitelisted by
IP address, only by name.
Some people hate DNSBL's because they or someone they know has at one
time or another been falsely listed (i.e. one of their own users
mistakenly reports them). Or perhaps they were listed for cause and
removed the spammer, but then had trouble getting delisted fast enough
to suit them or had to pay a fine. Despite what some detractors would
have you believe, a well-run MTA rarely winds up on a DNSBL.
I *personally* have been blacklisted. I know exactly what was on the
wire that month... NOTHING. I was across the country in Los Angeles
doing a TV show for a month and a half and the hardware was powered
down. Nothing was whistling into the DSLAM at all.
The reason (when I finally got in touch with the RBL admin) - "you
are in a netblock that's assigned to home/SOHO DSL".
And this was a relatively *reputable* RBL, mind you, not one of those
that once you are blacklisted (because someone didn't like you) you
must contact them to be removed - except you must contact them from
the blacklisted IP address -which- guess what- is blocked from delivering
Sorry, I hate dictatorships, and my personal experience has run to
indicate that RBLs are self-appointed tinhats of the first water.
> Adding an answerback at the end of DATA (like three-phase commit)
> would have been a nice thing, but it's a little late for that.
You can accept or reject at the end of DATA and you are theoretically
supposed to wait for the SMTP client to close the connection, so for
sane MTA's, this amounts to a three-way handshake of sorts. Spammers
may not wait around for your response, but a compliant MTA will return a
non-delivery notice to the sender for rejections at the end of DATA and
will hopefully return the error information you gave it. By rejecting
at the end of DATA, you've completed your responsibilities under SMTP.
If the sending MTA doesn't report the non-delivery to their user, that
MTA is broken, not yours.
True. But a three-phase commit would separate the pipeliners from
the more legitimate types.
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