The Spamhaus DBL (Domain Blocklist) is a list of domain names with poor reputations. It is published in a domain DNSBL format. These domain reputations are calculated from many factors, and maintained in a database which in turn feeds the DBL zone itself.
This listing occurs first on the domain level. Delivery for the domain will more than likely be impacted. If the blocked domain is found anywhere in your messages, delivery may be impacted and your IP may even be listed in the CSS list.
DBL listings may expire automatically after reputation factors change. To better understand the potential problems that caused the listing, review the DBL website. Once you have reviewed, you should then:
- Find and correct the root cause of the listing.
- Contact Mailgun and provide details on root cause and what was done to resolve. Mailgun will then start the removal request.
It is important that the issue be resolved prior to contacting Mailgun. Being honest and transparent will get you to a solution faster. Spamhaus is straightforward on what they want to know. If Spamhaus detects that a problem is ongoing they will not remove the block.