KONSTANT Blacklist

About the blacklist

The KONSTANT blacklist is a DNS based Blackhole List (DNSBL) set up to block spam emails typically found in Norway (Scandinavia). Typical spam include the normal back-scatter from any kind of business that target norwegian customers. Also, local marketing laws (covering unsolicited email) allow for companies to send unsolicited mail to other companies and this is quite common. In reality the marketing is rarely meant for the company, but rather targeting each employee. Examples include advertising fire wood, home alarm systems and leg warmers with remote control.

IP addresses are captured using spam traps and user submissions, and are manually moderated to prevent false positives.

The threshold for being blacklisted is "moderate to high" as at least local businesses usually adhere to "best practices" regarding unsolicited mail.

Some businesses use online mass mailers with questionable reputations. Some of these reuse (resell) opt-out addresses to other customers as they are verified to be working addresses. Some spam traps spesifically catch addresses that are reused after they have been unsubscribed from a service.


The KONSTANT blacklist is a free service that your email provider may choose to add to their list of DNSBLs. Almost all email provider use some kind of blacklist mechanism to minimize spam.

If you are an email provider in Norway you may add this list to your DNSBLs, it is provided free "as is". It is recommended to always use a whitelist in addition to any blacklist set-up to prevent false positives on critical addresses. Also feel free to feed the list with any addresses captured by your own systems by clicking on Submit above. (Yes, we are working on way to submit large amounts of addresses)

The address of the list is bl.konstant.no. See the documentation for your email system for more information on adding DNSBL/RBL lists.

Because the threshold for being blacklisted is relatively high and mainly focused on norwegian spam, you should not use this as the only DNSBL/RBL in your configuration. We recommend the following as a minimum:


The service is operated, maintained and hosted by Konstant AS.

If you have any questions regarding this service, please contact us at hostmaster@konstant.no. For abuse complaints, please use abuse@konstant.no.