DNS Blacklist with Exim
By setting the anti-spam DNS Blacklist feature in Exim you can eliminate a majority of your daily spam in a few simple steps.
This How-To is written for Debian Linux, with Exim using split configuration files. If your installation of Exim isn't utilizing split configuration, simply make all additions to your /etc/exim4/exim4.conf.template file.
Steps to follow
Edit the file /etc/exim4/conf.d/main/02_exim4-config_options and insert the following after the very last line.
# Added TODAYS-DATE by YOURNAME
# Spamhaus RBL zen.spamhaus.org
CHECK_RCPT_IP_DNSBLS = zen.spamhaus.org
Edit the file /etc/exim4/conf.d/acl/30_exim4-config_check_rcpt. Search for CHECK_RCPT_IP_DNSBLS acl and change the word "warn" to "deny" as shown below:
# Check against classic DNS "black" lists (DNSBLs) which list
# sender IP addresses
message = X-Warning: $sender_host_address is listed at $dnslist_domain ($dnslist_value: $dnslist_text)
log_message = $sender_host_address is listed at $dnslist_domain ($dnslist_value: $dnslist_text)
dnslists = CHECK_RCPT_IP_DNSBLS
Restart Exim so that our configuration changes take effect:
Once you have set up your mail server to use zen.spamhaus.org, you can test to see if the PBL blocking is working by sending an email (any email) to: firstname.lastname@example.org (you must send the email from the mail server which you wish to test). The Crynwr system robot will answer you to tell you if your server is correctly blocking PBL-listed IP addresses or not.
The email will look something like this.
250 mail.linuxlookup.com Hello nelson at pbl.crynwr.com [18.104.22.168]
550-X-Warning: 22.214.171.124 is listed at zen.spamhaus.org (127.0.0.10:
If everything is set-up correctly, you should see "Terminating conversation".