Know the moment you land on a blacklist.
A blocklist listing doesn’t throw an error — your email just quietly stops arriving. Merlonix re-checks your domain’s real IP addresses against DNS blocklists on a schedule and alerts you the moment a list names you, with the delisting link in hand.
How it works
01
Turn it on for an asset
Enable blocklist monitoring on any monitored asset — available on every plan. No mail-server change, no DNS change; we check the addresses your hostname already resolves to.
02
We resolve your real addresses
On the asset’s normal check cadence, Merlonix resolves your hostname’s IPv4 and IPv6 addresses — so what gets checked is what the world actually connects to, including addresses that change under you.
03
We query the blocklists
Each address is queried against a curated set of DNS blocklist zones the way mail servers do it — a reverse-IP DNS lookup per list — over encrypted DNS.
04
You get a listing alert with the way out
A new listing fires one warning naming exactly which lists you appear on, each with its own delisting-lookup link. When the listing clears, you get a recovery alert — confirmation your delisting worked.
Why continuous beats a one-time check
You find out before your customers do
The usual way teams discover a blacklist listing is weeks of quietly-vanishing email: password resets that never arrive, invoices in spam, reply rates falling. A scheduled re-check turns that silent failure into a same-day alert.
Checked like a mail server checks you
We query each blocklist the exact way receiving mail servers do — a reverse-IP lookup against the list’s DNS zone. No scraping, no third-party aggregator between you and the answer.
Engineered against false alarms
Some large blocklists refuse queries that arrive via shared public resolvers and signal that refusal in a way naive checkers misread as a listing. Merlonix classifies those as “no signal,” never as listed — so an alert from us means a list actually named you.
What we promise — and what we don’t
We watch the lists. Delisting stays yours.
Merlonix re-resolves your hostname’s addresses and queries them against DNS blocklists on your asset’s cadence. A new listing fires one warning naming the lists, each with its delisting-lookup link; a cleared listing fires a recovery alert. Lists that refuse public-resolver queries are recorded as “no signal,” never as listings. We cannot remove a listing for you — no one reputable can — but you will know the day it happens instead of the month after.
Common questions
What is a DNSBL / blacklist listing, and why does it matter?
DNS blocklists (DNSBLs) are public lists of IP addresses associated with spam or abuse. Receiving mail servers consult them in real time: if the address your domain resolves to is listed, your email gets rejected or spam-foldered — silently. A listing can also flag your site in security products. Because nothing errors on your side, most teams only notice weeks later.
How is continuous monitoring different from a one-time blacklist check?
A one-shot checker (including our own free /tools/blacklist) tells you whether you are listed right now. Listings happen later — after an IP-neighbor spams, a form gets abused, or your host recycles a dirty address to you. Continuous monitoring re-checks on your asset’s schedule and alerts on the transition, which is the moment you can still act before the damage compounds.
Which addresses do you check?
Every IPv4 and IPv6 address your monitored hostname currently resolves to — resolved fresh at each check, so address changes (new hosting, CDN shifts, dual-stack rollouts) are covered automatically. IPv6 addresses are checked against the lists that support IPv6 lookups.
Why do some blocklists not appear in my results?
A few large blocklists (for example Spamhaus and Barracuda) refuse lookups that arrive via large shared resolvers, and they signal that refusal as a special pseudo-listing response. Treating that as a real listing would false-alarm every domain, so Merlonix honestly classifies those responses as “no signal” instead. Lists that answer public-resolver queries — such as SpamCop and UCEPROTECT — carry your result.
Can you get me delisted?
No — and be wary of anyone who says they can. Delisting is requested by the IP’s owner directly with each list operator, usually via a self-service form. What we do is tell you immediately which list named you, link you straight to that list’s delisting lookup for your address, and then confirm with a recovery alert when the listing actually clears.
Which plans include it?
Blocklist monitoring is included on every plan, including Free — see the pricing page for the full comparison. For a one-time check without an account, use the free blacklist checker.
Stop discovering listings from your bounce rate.
Turn on blocklist monitoring and get the alert the day a list names you. Start the full-workspace trial — 14 days, no card.