I concur, lately I've found list.dsbl.org to be not particularly useful. That
list works like this:
1) someone nominates the IP address as a potential open relay
2) the dsbl.org machine attempts to relay through the IP address
3) if an e-mail can be relayed through the IP address, then the IP address will
be listed for a long time
Clearly this is not a very good solution for spam from dynamic IP addresses.
The open relay will change IP addresses every time it connects, leaving the
previous dynamic IP address listed for a long time. This DNSBL is clearly a
holdover from the days before botnets. And,
http://www.sdsc.edu/~jeff/spam/cbc.html seems to suggest low intercept rates
for this blacklist. I do remember a few years ago when the dsbl.org blacklist
was more useful. Now, I find Spamhaus, Spamcop, and Sorbs much more useful.
On a lightly loaded server, the list.dsbl.org blacklist might rate 0.5 points
in a weighted system like Spamassassin -- not nearly enough to cause rejection
unless other factors weigh in heavily.
----- Original Message -----
From: Enrique Verdes
To: Leigh S. Jones, KR6X
Sent: Monday, March 03, 2008 6:27 AM
Subject: Re: [courier-users] how to whitelist rbl blacklisted e-mail
Sorry, I should have given more details. I'm using dns black lists in the
BLACKLIST variable of the esmtp file. The one giving me problems is dsbl.org,
which I removed, at least until find a better solution, but given Jay Lee
advice this would be forever.
Leigh S. Jones, KR6X wrote:
Although Jay Lee gives good advice, there is more information to be given.
First of all, the whitelisting and manual blacklisting is done by adding IP
blocks to a file in the directory /etc/courier/smtpaccess. Well, this
directory could be changed during the build process, but that is the normal
place for it. If you find a file named "default" in that directory, it will
show you the way to do it. My directory also contains a file generated by
the webadmin, which is my favorite place to enter such changes.
At this time, there has been 2 distinct IP addresses from the Google's IP
block.
I can't tell how many of those IPs are blocked, so I think the best aproach
is to remove dsbl.net from my list.
Thanks for your advice.
Yes, it's easiest to make these changes in the webadmin.
If you are not using the webadmin, then you'll need to run
/usr/lib/courier/makesmtpaccess after making changes to the
/etc/courier/smtpaccess contents.
----- Original Message -----
From: "Jay Lee" <[EMAIL PROTECTED]>
To: "Enrique Verdes" <[EMAIL PROTECTED]>
Cc: "Lista courier-users" <[email protected]>
Sent: Monday, March 03, 2008 5:25 AM
Subject: Re: [courier-users] how to whitelist rbl blacklisted e-mail
On Mon, Mar 3, 2008 at 8:17 AM, Enrique Verdes <[EMAIL PROTECTED]>
wrote:
I'm having some trouble with a customer that's using GoogleApps to handle
it's email. Some of the google's IP address are blacklisted, so some
emails from this customer are being blocked. I've been looking at courier
config files and can't find a way to whitelist my customers domain name.
Blacklisted by what? What does your BLACKLISTS= setting look like in
/etc/courier/esmtpd?
What would be the better aproach to solve this problem? There's a config
option or file where I can whitelist domains affected by this problem?
The best way would be to determine what blacklist is braindead enough
to block Google and stop using it. We all know that some spam is sent
out by Hotmail, GMail and Yahoo Mail servers but a *lot* of legit mail
from users comes from these big three also, I recommend you use a
blacklist service like Spamhaus that is much more cautious about
blacklisting an IP address. I've used them for nearly 4 years now and
have 0 false positives to report. I rely on local filtering
(SpamAssassin) to catch spam from IPs that Spamhaus was to
conservative to block.
Jay
--
Jay Lee
Network / Systems Administrator
Information Technology Dept.
Philadelphia Biblical University
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------------------------------------------------------------------------------------------------------------------
Enrique Verdes
UyGroup Consulting & Technology
www.uygroup.com.uy
Av. Gral. Paz 1481 - CP 11400
Montevideo - Uruguay
Phone/Fax: (+598-2) 600-6200 - ext. 223
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