Spamhaus ZEN Explainer
ZEN is the combined zone most mailbox providers query. Each sub-list (SBL, XBL, PBL) gets you blocked for different reasons.
What: Manually-listed IPs of known spam sources. Used by ~90% of major MBPs.
Cause: A human Spamhaus volunteer determined your IP is the source of spam.
Removal: Fix the underlying cause (compromised account, list problem) and apply via Spamhaus removal form. Usually delisted within 24-48h if cause is fixed.
What: Automated detection of compromised hosts and known botnet IPs.
Cause: Your IP was seen sending spam from a botnet, or your server is open-relay / proxy-abusable.
Removal: Close the compromise (patch, reset credentials, audit relay config), then auto-delisting starts within hours of clean behavior.
What: IPs that should not be sending mail to begin with. residential, dynamic, dial-up ranges.
Cause: Your IP is in a range your ISP told Spamhaus shouldn't be a mail sender.
Removal: You can self-remove from PBL if you have permission from your ISP to send mail. Or: switch to a static/business IP range.
You know the rule. See where you sit against it.
Reference pages tell you the benchmark. Outsolvi tells you whether your team is above or below it. per-rep, per-deal, per-week. and which behavior changes move the number. From $7/user/mo yearly.
See your numberExplains SBL (manually-listed spam sources), XBL (automated detections / botnets), PBL (policy block. IPs that shouldn't send mail), and the removal process for each.
After a Spamhaus listing. Before assuming your deliverability problem is something else.
FAQ
What's the difference between SBL, XBL, and PBL?+
SBL is a manual listing by a Spamhaus analyst who decided your IP is a spam source. XBL is automated detection of compromised or botnet hosts. PBL is a policy listing that says this IP range was never supposed to send mail at all, like residential or dynamic addresses.
Does this page look up my IP on Spamhaus?+
No. It explains what each sub-list means and how removal works for each one. The actual lookup and the removal request both happen on Spamhaus's own site.
How fast does delisting happen?+
It depends on the list and on whether you fixed the cause. XBL tends to clear within hours once the compromise is closed, SBL removals are usually processed within a day or two after you apply, and PBL can be self-removed if your ISP permits you to send mail.
Keep going
Articles, glossary entries, and other tools on the same topic.
Nate built Outsolvi after watching every email-tracking tool he had ever used lie to him about opens. Outsolvi runs Tier 1 to 5 confidence scoring on every open, native in Outlook and Gmail, so the number on the dashboard is one a rep can actually act on.
We update these pages when the underlying mechanics change. new mailbox-provider rules, new tracker behavior, new measurement gaps. The dates above are real revisions, not auto-touches.