2015-03-13 22:34:58 -06:00
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< title > Enable DNSBL service in Postfix to reduce spam< / title >
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< / div > < h1 id = "enable-dnsbl-service-in-postfix-to-reduce-spam" > Enable DNSBL service in Postfix to reduce spam< / h1 >
2015-06-13 11:07:45 -05:00
< blockquote >
< p > 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 limit
DNS queries. Also, mail service higly relies on DNS queries, so a local
DNS server speeds up the mail flow.< / p >
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2015-03-13 22:34:58 -06:00
< p > You can enable additional DNSBL services in Postfix to reduce spam. We use
< code > zen.spamhaus.org< / code > for example below.< / p >
< ul >
< li > Open Postfix config file < code > /etc/postfix/main.cf< / code > or
< code > /usr/local/etc/postfix/main.cf< / code > (on FreeBSD), append
< code > reject_rbl_client zen.spamhaus.org< / code > to parameter < code > smtpd_recipient_restrictions< / code > .
Final setting looks like below:< / li >
< / ul >
< pre > < code > smtpd_recipient_restrictions = ..., reject_unauth_destination, reject_rbl_client zen.spamhaus.org
< / code > < / pre >
< p > It must be placed after < code > reject_unauth_destination< / code > . You can add more DNSBL
services after < code > reject_unauth_destination< / code > , and they will be queried in the
specified order.< / p >
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< li > Restart or reload Postfix service is required.< / li >
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< h2 id = "references" > References< / h2 >
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2015-03-13 23:03:38 -06:00
< li > < a href = "http://www.postfix.org/postconf.5.html#reject_rbl_client" > Postfix Configuration Parameters: reject_rbl_client< / a > < / li >
2015-03-13 22:34:58 -06:00
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< p > < a href = "http://www.spamhaus.org" > Spamhaus website< / a > < / p >
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< li > < a href = "https://www.spamhaus.org/organization/dnsblusage/" > Spamhaus DNSBL Usage Terms< / a > < / li >
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