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Stop using zen.spamhaus.org as a DNSBL example on the Mail Server Settings page

danami

Silver Pleskian
Username:

TITLE

Stop using zen.spamhaus.org as a DNSBL example on the Mail Server Settings page

PRODUCT, VERSION, OPERATING SYSTEM, ARCHITECTURE

Product version: Plesk Obsidian 18.0.52.3
OS version: AlmaLinux 8.7 x86_64
Build date: 2023/05/16 12:00
Revision: a3b74dbc9de2e47afd4e532d02fa7759b29d3fa5

PROBLEM DESCRIPTION

The SpamHaus RBL no longer accepts RBL DNS queries from any public resolver, including if you are using it as a forwarder. SpamHaus RBL is blocking all email if your server is using an open resolver. For example, public DNS resolvers like Google, Quad9, Cloudflare DNS or via any DNS server that is attempting a high volume of queries against SpamHaus without being registered with them. The mail logs will indicate the issue like this:

Code:
Client host [XXX.XXX.XXX.XXX] blocked using zen.spamhaus.org; Error: open resolver; https://www.spamhaus.org/returnc/pub/203.0.113.1

STEPS TO REPRODUCE

Set Tools and Settings -> Mail Server Settings -> DNS zones for DNSBL service to zen.spamhaus.org

ACTUAL RESULT

DNSBLs should work regardless of what DNS servers you are using.

EXPECTED RESULT

The average user doesn't know what public DNS resolvers are. All they know is that mail stops working once zen.spamhaus.org is set as a DNSBL.

ANY ADDITIONAL INFORMATION

How can I fix the error: Client host [XXX] blocked using zen.spamhaus.org; Error: open resolver; - Knowledgebase - Danami

YOUR EXPECTATIONS FROM PLESK SERVICE TEAM

Confirm bug
 
I see the valid argument and have asked product management how to proceed. It's not a bug, but you are absolutely right, that this example can cause issues for many users.
 
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