ZapBL RHSBL is a domain-based blocklist that lists domains found within spam emails received by ZapBL administrators, with most listings on this blacklist automatically expiring over time.
The ZapBL RHSBL is a domain-based blacklist (RHSBL) that lists domains found in emails that ZapBL administrators consider to be spam. Unlike IP-based blocklists, this one focuses specifically on the domain names used in unwanted emails. Mail server administrators can choose to use this list to filter incoming mail.
Technically, it functions as a Domain Name System Blocklist (DNSBL). A mail server queries the list by taking the domain in question, for example, 'example.com', and prepending it to the ZapBL RHSBL zone name. The full query would look like 'example.com.rhsbl.zapbl.net'. If the query returns a specific IP address, in this case 127.0.0.2, it signals that the domain is on the blacklist.
The ZapBL RHSBL blocklist is operated by the organization ZapBL. Their listing philosophy is based on the personal opinions of their administrators. They state that they are not labeling anyone a spammer, but are simply maintaining a list of domains from which they no longer wish to receive email. Any administrator who uses this list does so by their own choice.
A domain can be added to this blacklist for several reasons, all based on emails received by ZapBL administrators:
The removal process for the ZapBL RHSBL depends on the nature of the listing. Most listings are not permanent and will expire automatically after a period of time. For a more proactive approach, you can use their lookup tool to check your domain. If a removal option is available for your listing, it will be presented there.
If your listing is not set to expire and does not have a public removal option, you must contact ZapBL directly. However, they have a strict communication policy. They will only communicate with the registered abuse contact for the domain, which is typically the abuse@ address. If you are an end-user, you must have your Internet Service Provider or domain administrator contact them on your behalf. You can submit your delisting request through their Contact Us form. An 'Express Delisting' option, which involves a paid manual review, is also available.
The impact of being on the ZapBL RHSBL blocklist is generally considered low. It is not one of the major blacklists used by large mailbox providers like Gmail or Microsoft. However, its use by smaller, independent, or specialized mail server administrators means that a listing could cause email delivery failures to specific recipients. While not a critical blacklist for most senders, being listed is a negative signal about your domain's reputation and should be addressed to ensure complete mail delivery.
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