Copyright 2002 Notwise-Labs under the You Break it You Buy it License. (GNU-YBBL)
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What is an RBL list?
An RBL style list is a basicly a DNS server that maintains a list of known spam rlays. It is used by sendmail (or another MTA) when mail is recived. The MTA will make a standard DNS query to the list server of your choice and reject the incoming mail if the server it originated from is listed in the RBL server. This will cause incoming spam to be rejected without even having the message come to your server and waste your bandwidth. | |
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Adding a list to your sendmail config the easy way.
RedHat and Mandrake Systems: Both of these systems (and others based off of RedHat ship with a file /etc/mail/sendmail.mc that is a complete set of m4 macros needed to generate a fres /etc/sndmail.cf The easiest approach is to open this file in your favorite text editor and add a line like this, FEATURE(dnsbl, `relays.osirusoft.com', `Rejected - see http://relays.osirusoft.com')dnl FEATURE(`dnsbl', `relays.ordb.org', `Rejected - see http://ordb.org/')dnl As you can see I have two in mine, there are other lists to wich I will link to below. This strictly speeking is not needed, in fact more then one will cause a performance hit but will catch more spam so it is up to you as to what your needs are. You could even include more, MAPS maintains 3 different lists plus a fourth that includes all three but they now charge for access if you site is in any way commercial. After adding those lines to your sendmail.mc file all you need to do is as root execute the following command from the /etc/mail dir. m4 sendmail.mc > ../sendmail.cf It would be a good idea to back up your old /etc/sendmail.cf beforehand. After running the m4 comman restart sendmail and you are done. FreeBSD On release 4.4+ the file you need to edit is, /etc/mail/freebsd.mc Other Linux/Unix systems: If your running sendmail setup will be very similar but the file locations are probally different, I will add exact instructions shortly after looking on a few of these machines. Other MTA's There is a large listing of other MTA's and how to set them up here, http://www.mail-abuse.org/rbl/usage.html |
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Testing your setup.
You can use the following command and inputs to verify your setup. sendmail -bt -C /config/to/test/sendmail.cf > .D{client_addr}127.0.0.1 > Basic_check_relay <> rewrite: ruleset 192 input: < > rewrite: ruleset 192 returns: OK > .D{client_addr}127.0.0.2 > Basic_check_relay <> rewrite: ruleset 192 input: < > rewrite: ruleset 192 returns: $# error $@ 5 . 7 . 1 $: "Mail from " 127 . 0 . 0 . 2 " refused; see http://www.mail-abuse.org/cgi-bin/lookup?127.0.0.2" > CTRL/D The output/responses will be slightly different depending on your sendmail version and the list you used. |
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An incomplete listing of RBL style lists.
Open relay Database Osirusoft's Open Relay Datatbase Spamhaus.org Note that Osirusoft's database contains a copy of the spamhaus db. MAPS The original but now non free spam relay laist. Aslo the best organised and if you can afford it probally the best. Free access is avaliable for hobby sites. |
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