The DNS server is blocked by a Spam URI Realtime Blocklist

As of version 13.1, NoSpamProxy warns if a DNS server used is blocked by a Spam URI real-time block list.

Problem

This message informs you that the DNS server you are using, which you have configured in the Windows network settings or via the NoSpamProxy Command Center at Configuration > Connected Systems > DNS Server, is blocked on the named Spam URI Realtime Blocklist. All DNS queries to the UriBL are therefore not answered and the spam defence is slightly weakened.

In most cases, the reason for this is that the free queries from the requesting DNS server have been used up, as the lists only allow a certain number of free queries.

Solution

The following options allow further requests beyond the free limit of the Spam URI Realtime blocklists:

• Disable features like QNAME Minimization (RFC 7816) for the NoSpamProxy gateway role to reduce the number of requests

• Use of your own DNS server, through which only your queries run (recommended)
• Change the DNS provider where the limit is not yet used up (not recommended)
• Registration with the operator of the Spam URI Realtime Blocklist, to send requests beyond the free limit (subject to a fee, independent from the DNS server)

A different DNS server can be set without much effort via the NoSpamProxy Command Center at Configuration > Connected Systems > DNS Server. After setting a new DNS server, the service of the gateway role(s) must be restarted to clear the DNS cache.

We cannot make recommendations for DNS servers, as there are a large number of free providers in this area.

NOTE: In addition, we would like to point out that this problem is not caused by NoSpamProxy and must be communicated with the corresponding operator of the DNS service.