elmau
/
iredmail-doc
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity
iredmail-doc/en_US/howto/enable.dnsbl.md

1.6 KiB
Raw Blame History

Enable DNSBL service in Postfix to reduce spam

!!! note "Important Note"

If you're running a high-traffic mail server, you'd better setup a local
DNS server to cache DNS queries, because free RBL services like
`zen.spamhaus.org` may improperly reply if your server exceed the DNS
query limit. Also, mail service higly relies on DNS queries, so a local
DNS server speeds up the mail flow.

You can enable additional DNSBL services in Postfix to reduce spam. We use zen.spamhaus.org for example below.

  • Open Postfix config file /etc/postfix/main.cf or /usr/local/etc/postfix/main.cf (on FreeBSD), append reject_rbl_client zen.spamhaus.org to parameter smtpd_recipient_restrictions. Final setting looks like below:
smtpd_recipient_restrictions =
    ...
    reject_unauth_destination
    reject_rbl_client zen.spamhaus.org

It must be placed after reject_unauth_destination. You can add more DNSBL services after reject_unauth_destination, and they will be queried in the specified order.

  • Restart or reload Postfix service is required.

!!! note "Another popular DNSBL server"

Another popular DNSBL server address is `b.barracudacentral.org`. For more
details, please read its web site:
[Barracuda Reputation Block List (BRBL)](http://www.barracudacentral.org/rbl)

See also

References