DNSBLs and RBLs
GreenArrow Engine can optionally use DNSBLs (DNS-based Blackhole Lists), such as the ZEN Spamhaus List to filter incoming mail.
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    To control which DNSBLs to use, list them one per line in the /var/hvmail/control/smtp.rblsfile. For example:echo "zen.spamhaus.org" >> /var/hvmail/control/smtp.rbls
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    To disable checking DNSBLs, delete the /var/hvmail/control/smtp.rblsfile:rm -f /var/hvmail/control/smtp.rbls
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    Apply changes by restarting the SMTP service, and verifying that it stays up: svc -t /service/hvmail-qmail-smtpd sleep 7 hvmail_init status | grep "hvmail-qmail-smtpd "If the SMTP service does not show the status “UP”, reverse your change. 
