Email Blacklist Monitoring With Five-Minute Alerts.

Email blacklist monitoring is the automated, scheduled checking of your sending IPs and domains against DNS blocklists (DNSBLs/RBLs) such as Spamhaus, Barracuda, and SpamCop, with an alert the moment a new listing appears. Verifox checks 200+ lists every hour and notifies you within 5 minutes of a change, so you fix the problem before a campaign goes out blind.

Run a one-off lookup: the free email blacklist check queries the major DNSBLs and shows where you stand today, no signup needed. That covers the snapshot. For ongoing coverage, add the IP or domain to monitoring here so the same sweep repeats every hour and you hear about new listings instead of discovering them weeks later.

Every hour, around the clock, for every IP and domain you monitor, across 200+ blacklists. When a result flips from clear to listed, the alert goes out within 5 minutes by email, Slack, or webhook. After a delisting, we keep checking hourly for 7 days to confirm you stay clear and were not silently re-listed.

Three causes dominate: hitting spam traps (addresses planted to catch sloppy list hygiene), complaint spikes (even 3 spam reports per 1,000 recipients can trigger aggressive lists), and compromised accounts or open relays pumping out spam under your name. Routine email verification before every send removes the traps and dead mailboxes that start most of these incidents.

Fix the root cause first, then file the removal request. Spamhaus requires a manual request through its Blocklist Removal Center and rejects you if the underlying issue persists. Barracuda has its own reputation removal form. Verifox identifies which list flagged you, links the correct removal page, and explains that list's specific requirements, then re-checks hourly so you know the moment the removal lands.

Some do. SORBS entries typically age out around 48 hours after the spam stops, and several smaller DNSBLs auto-expire on similar timers. The lists that matter most do not: Spamhaus keeps you listed until the cause is fixed and a removal request is approved. Either way, if the root problem remains, expiry just buys you days before the re-listing.

An IP blacklist (RBL/DNSBL, like Spamhaus ZEN) lists the server address you send from, so receiving servers reject the connection itself. A domain blacklist (DBL/URIBL, like Spamhaus DBL or SURBL) lists your domain name, so any message containing it, in the From address or in a link, gets flagged even from a clean IP. Verifox monitors both for every asset you add.

Severely. A Spamhaus ZEN listing means most major mailbox providers reject your mail at the SMTP handshake, before spam filtering even runs. Smaller lists tilt filtering decisions toward the junk folder. Because rejection is silent, open rates sag with no bounce report to explain why. Pair monitoring with deliverability monitoring to see the placement impact, and a domain spam check to rule out content flags.

Yes. Alerts deliver by email, Slack, or any webhook endpoint, and the webhook payloads are documented in the API reference so you can route listings straight into PagerDuty, Opsgenie, or your own tooling. The median alert time after detection is under 5 minutes. AI agents can consume the same data through the native MCP server.

Starting is free: create an account and you get 1,000 free credits, or 2,500 if you sign up with a work email. No card required, and credits never expire, so nothing forces you onto a subscription.