Distributed Sender Blackhole List - Delisting

Delisting

For an IP address to be removed from DSBL's lists, the administrator of the IP address must demonstrate "accountability" by first requesting, and then responding, to a delisting message from DSBL. The message can only be sent to the postmaster or abuse desk of the listed IP address. The postmaster's e-mail domain is determined by consulting reverse DNS.

Until this accountability test is passed, the host remains listed. Thus it is possible that some of the IP addresses listed by DSBL have been secured, but are still listed because the administrator has not demonstrated accountability by requesting and responding to a de-listing message.

Because DSBL does not perform vulnerability tests, the only criterion for removal is this accountability test. It is entirely possible that hosts that are delisted are still vulnerable to abuse. If this is the case, it is expected that the host will be relisted by a tester the next time it is abused.

The problem with the delisting process is that dynamic dial-up IP-addresses which make it to the list will never be delisted since delisting would require to run an SMTP-server in the temporary dial-up IP. Another problem is that they require the SMTP server to be running behind a router that allows packets marked with the ECN bits. This may require an upgrade to the newest router software before the accountability email can be received.