This RHSBL run by Spamhaus contains domains (typically web site domains) found in spam messages.
The list is maintained by a dedicated team of specialists working with an automated system that constantly analyses a large portion of the world's email flow and the domains used in spam emails.
Spamhaus Dbl Is A Right-Hand Side Blacklist
Domain-based Blacklists are also commonly referred to as Right-Hand-Side Black Lists (RHSBL), and as such list actual domain-names as opposed to IP addresses of outbound email servers. This would likely be as a result of your domain name being reported as sending Unsolicited Bulk Email (UBE) as opposed to your Sending MTA (Mail Transfer Agent), i.e. your outbound email server IP Address.
Spamhaus Dbl Requires A Manual Delisting Request
This blacklist does support a manual request to remove or delist your IP Address from their database. Please note that removal requests that are submitted without addressing the core problem will likely result in your IP Address or Domain being relisted in that database, which can cause subsequent problems and extended listing periods without release.