The CleanTalk DNSBL Service Usage

CleanTalk provides a special DNSBL service to check IP for spam in accordance with its DNS name. This will be helpful in usage in an SMTP server configuration. More info about the DNSBL conception can be found there.

Examples of Usage in Postfix, Sendmail, SpamAssassin

You can use these examples to integrate the DNSBL check of IP addresses. Your DNSBL token can be found in the Blacklists API mode of CleanTalk dashboard https://cleantalk.org/my/?cp_mode=api

1. Example for Postfix:

In the main.cf file add the next record:

smtpd_recipient_restrictions = reject_rbl_client <your_dnsbl_zone_key>.dnsbl.cleantalk.org

2. Example for Sendmail:

In the sendmail.mc file add the next record:

FEATURE(`dnsbl', `<your_dnsbl_zone_key>.dnsbl.cleantalk.org', `"Spam detected, see: https://cleantalk.org/blacklists/"$&{client_addr}')dnl

3. Example for SpamAssassin:

In your config file (often found in /etc/mail/spamassassin/local.cf) add the next lines:

header MY_RULE eval:check_rbl('cleantalk','<your_dnsbl_zone_key>.dnsbl.cleantalk.org.')
describe MY_RULE Entries listed in dnsbl.cleantalk.org RBL
score MY_RULE 2.0