as nerdy as needed.


Purpose of the DNS-based blackhole list (DNSBL)

This list mainly exists as an additional SPAM-prevention layer for the mail solution used here. Still, maximum effort is put into keeping it as useful as possible for public usage too.

Listing policy and return values

One of the following points will get an IP address listed:

  • Sending SPAM to specific mail addresses
  • Suspicious login attempts
  • Abuse of SPF

When listed, a query for the example IP will return an A record with "" and a TXT record like this:

$ dig +short -t ANY
" is listed because of misbehaviour. See for details"


View the whole list and query it manually.


Not available. All bans automatically expire after 7 days. There is one exception for the UCEPROTECT network: they can profit from a permanent entry on the DNSBL. Reading material available at 1, 2, 3, 4 and 5.

Use the DNSBL in your mail setup

Add to your existing RBL setup to query the blacklist.

Trouble? Get in contact

In the unlikely case that your IP was blocked in error, please contact us and provide as much details as possible:

  • Date and time when you detected the issue
  • Sender and recipient addresses
  • Your mail server's public IP address(es)
  • Explanation of what countermeasures have been taken