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HRBL is a DNS based blacklist provider.

You can use it on your mailserver in different ways, just like any other common blacklists like Spamhaus or Spamcop.

This service is free of charge. To lower the load use your own or your own ISP's caching nameserver please.

To manually check if an IP address or hostname is listed in HRBL or not, you can use the checking page too.


If you want to know if the IP address of your SMTP client (say is listed in HRBL, then query the A record of

If you want to check if an SMTP client's hostname or domain name (say is listed in HRBL, then query the A record of

If you get back from either blacklist, then it is listed. The TXT record contains the error message you can give to your remote SMTP client. Don't worry, most modern MTAs do this fully automatically. Just set up using and Check your MTA's documentation how to use a standard DNS based blacklist.

In Postfix, for example, you could write:

smtpd_recipient_restrictions =



Spamassassin can score up messages that have been received via hosts that are listed in HRBL:

header RCVD_IN_HRBL eval:check_rbl('hrbl', '')
describe RCVD_IN_HRBL Received via a relay in HRBL (
tflags RCVD_IN_HRBL net
score RCVD_IN_HRBL 3

It can also look up links in incoming messages if they are listed in HRBL:

urirhssub URI_IN_HRBL A 2
body URI_IN_HRBL eval:check_uridnsbl('URI_IN_HRBL')
describe URI_IN_HRBL Contains a URI listed in
tflags URI_IN_HRBL net
score URI_IN_HRBL 3

If you have bumped into an unresolvable problem, contact us.