IP Blacklist (RBL/DNSBL) Checker Explainer
Not all blacklists are equal. Being on Spamhaus ZEN is reputation-killing; being on a no-name list usually isn't. This guide explains.
| RBL | Weight | Note |
|---|---|---|
| Spamhaus ZEN (sbl + xbl + pbl) | Critical | Most MBPs query Spamhaus ZEN directly. Listed = high spam-folder rate or outright reject. |
| Barracuda Reputation Block List (BRBL) | Major | Heavily weighted by mid-market MTAs (Exchange, on-prem). Removal via Barracuda Central. |
| SpamCop (bl.spamcop.net) | Moderate | Auto-lists on complaint volume; auto-delists after 24h of no complaints. Watch but don't panic. |
| SORBS | Low | Mostly residential / dynamic IP blocklist. Matters if you're on a VPS provider with a poor IP range. |
| UCEPROTECT (levels 1-3) | Minimal | Few major MBPs actually query it. Some hosting providers do. Removal is paid-only at higher levels, which is itself controversial. |
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 numberLists the major RBLs (Spamhaus ZEN, Barracuda, SORBS, SpamCop, UCEPROTECT), their weight in inbox-placement decisions, and how to check.
Any deliverability investigation. Always check Spamhaus first.
FAQ
Does this check whether my IP is blacklisted?+
No, despite the name. It's a reference table of the major blocklists and how much weight each one carries. To find out if you're listed you run the lookup at the blocklist's own site, starting with Spamhaus.
I'm on a blocklist I've never heard of. Should I panic?+
Probably not. Spamhaus ZEN is the one most mailbox providers actually query, and Barracuda matters for on-prem Exchange. SORBS and UCEPROTECT are queried by far fewer receivers, so a listing there rarely explains an inbox problem on its own.
Why is SpamCop listed as only moderate?+
SpamCop lists automatically on complaint volume and delists automatically after about 24 hours with no new complaints. It's worth watching as a signal that something changed, but it usually clears itself.
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.