SORBS (Spam and Open Relay Blocking System) was not one blocklist but a bundle of separately-queried zones, each targeting a different kind of abuse. Proofpoint, which had run SORBS since 2011, shut the entire service down on 5 June 2024. Every zone below stopped being maintained on that date, and there is no delisting process for any of them — a checker reporting a SORBS hit today is reading a stale, unmaintained zone file, not a live listing.
This post exists because guides describing SORBS sub-list removal are still widely circulated, and the sub-list names still show up in old filter configurations and documentation. Here is what each one covered, for context, and what to actually check instead.
The sub-lists, as they existed
| Sub-list | What it targeted |
|---|---|
| Spam blacklist | IPs that had directly sent spam to SORBS's spam traps |
| Open relay blacklist | Mail servers configured to relay mail for anyone, a classic spam-abuse vector |
| Trojan / hacked server list | Hosts showing signs of compromise, often spam-sending malware |
| Dynamic IP list (DUHL) | Consumer and dynamically-assigned IP ranges, on the basis that legitimate mail servers rarely run on them |
| Non-Delivery Report (NDR) list | IPs generating backscatter — bounce messages sent to forged senders |
| Zombie / compromised host list | Hosts behaving like part of a spam botnet |
| Escalation tracking | A time-based mechanism that treated repeat or unresolved listings more severely the longer they persisted |
None of these had meaningfully different removal procedures from each other in the end — all delisting for any SORBS zone ran through the same SORBS web form, which no longer exists.
What a SORBS reference means if you see one today
- In a multi-list checker report: a stale cached answer or a tool that hasn't removed SORBS from its zone list. Not evidence of an active block.
- In a mail server's own reject reason: that server's spam filter still queries a dead SORBS zone. Dead DNSBL zones can behave unpredictably, including answering positive for everything, which makes this worse than simply ineffective — it can block mail that was never actually suspect.
- In your own filter configuration (Postfix, Exim, a UTM appliance): remove the SORBS zone entry entirely. There's no benefit to querying it and a real risk of false positives from an abandoned, unmaintained zone.
If a receiver's server rejects you citing SORBS
There's no delisting path to follow because the service doesn't exist. Contact that receiver's postmaster directly, state that SORBS was decommissioned on 5 June 2024, and ask them to remove the zone from their mail filter configuration. This is a configuration problem on their end, not something fixable from your sending side.
The concern behind the DUHL sub-list is still real
The DUHL specifically targeted dynamic and consumer IP ranges, and that underlying concern didn't disappear with SORBS — Spamhaus's PBL (Policy Block List) covers the same ground today and is actively maintained. If your sending IP is in a dynamic or residential range, that's worth fixing on its own merits regardless of SORBS.
What not to do
- Don't follow a guide's SORBS removal steps. Every such guide describes a form that no longer exists.
- Don't pay anyone offering "SORBS delisting" as a service. There is nothing to delist; this is either a mistake or a scam.
- Don't leave a SORBS zone configured in your own mail filtering stack. An unmaintained zone is a liability, not a safety net.
- Don't assume a tool that still lists SORBS as an option is trustworthy by default. Plenty of free checkers haven't been updated to drop retired zones; that's a maintenance gap in the tool, not evidence about your IP.
Why this keeps confusing people
SORBS operated for roughly two decades before shutting down, which means an enormous amount of documentation, forum advice, filter-configuration templates, and SEO-optimised "how to delist" content about it was written and indexed while it was still active. None of that content updated itself when the service closed. If you land on a page describing SORBS removal steps dated earlier than mid-2024, treat it as historical record rather than a current process — the underlying service it describes is gone regardless of how recently the page was republished.
What to check instead
Spamhaus ZEN and DBL, Barracuda BRBL, SpamCop SCBL, the SpamRats zones, and Invaluement's ivmSIP/ivmURI cover the ground SORBS used to, and all of them are actively maintained with working removal processes.
MailPilot's blocklist monitoring is weighted toward lists receivers actually consult today, so a stale SORBS-era result doesn't crowd out a current, actionable listing, and the historical sub-list names above don't need to be memorised to make sense of an old report that still mentions them.
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