Find out when your domain is put on a blocklist.

If your domain ends up on a blocklist, your site still works when you open it, and uptime checks still pass. But some visitors can't reach the site, and email from your domain goes to spam. Barkme checks for this every day.

Why uptime checks miss it

An uptime monitor asks one question: does the URL answer with a 2xx or 3xx status? A blocklist listing doesn't change that answer. Your server is fine. The problem sits between your visitors and the server, in the DNS resolver they use or in the spam filter that reads your email.

Many offices, schools, routers and security apps use filtering DNS. When a filtering resolver has your domain on its threat list, it answers with a block address or with nothing at all, so the browser never reaches your server. On your own laptop, with an ordinary resolver, the site loads as usual. Mail works the same way. A receiving server that checks Spamhaus DBL sees your domain listed and files your invoices and password resets as spam, while your own test emails arrive fine.

That is why listings often go unnoticed for days. Nobody on your team sees a symptom. There is more on how this happens in why a blacklisted domain stops resolving for some visitors.

What is checked

Web filters. Barkme checks whether security DNS services, such as Cloudflare's filtered DNS and AdGuard, block your domain. If one does, it asks Quad9 which threat list is responsible. The check compares each filtering resolver's answer with the answer from clean resolvers that don't filter. If the clean resolvers return your server's address and a filtering resolver returns a block address or no answer, that counts as a listing.

Mail blocklists. Barkme looks up your domain on Spamhaus DBL, SURBL and URIBL. These lists decide whether email and links from your domain are trusted. They list domain names, so Barkme looks up the domain itself.

Set it up in three steps

1. Verify the domain. Add one TXT record on the apex, with host @ and the value barkme-verify= followed by the token Barkme shows you. It usually takes about two minutes. Barkme keeps checking until the record appears, and verifying the apex covers every subdomain beneath it.
2. Leave the reputation checks on. Once the domain is verified, both tracks run once a day with nothing to schedule. Each track has its own switch on the domain, so you can turn off the mail track for a domain that never sends email and keep the web track.
3. Connect a channel. On the Free plan, alerts go by email. Paid plans add Slack and Telegram, and Pro adds a signed webhook. Every channel sends a test alert when you connect it, so you know it works before a real listing.

While you are there, add monitors for the domain's main URLs. They cover the other half of the picture: whether the site answers at all.

When you get alerted

You get one alert when your domain is listed, with the names of the lists, and one more when it is removed. If a blocklist refuses or limits the lookup, Barkme does not count that as a listing, so you don't get false alerts.

Removal can take days. If you were alerted every day the domain stayed listed, the alerts would turn into noise and someone would mute them. One alert at the start and one at the end keeps each of them worth reading.

What a listing alert looks like

Say an old subdomain on acme-shop.com still runs a forgotten WordPress install, and someone has put a phishing page on it. Spamhaus adds the domain to the DBL. The next daily check finds it, and this arrives by email:

acme-shop.com - Mail reputation listing detected

Domain: acme-shop.com
Track:  Mail reputation
Source: dbl.spamhaus.org (127.0.1.4)

The source line tells you where to go. Spamhaus, SURBL and URIBL each have their own lookup and removal pages. Fix the cause first: take the page down, change the passwords, clean up the files. Then ask the list for removal. Lists are far more willing to remove a domain once the problem is gone.

When a later daily check finds the domain clean, a second alert says the listing has cleared. There is nothing to close by hand. A web track alert reads the same way, with the filtering resolver as the source and, when Quad9 has it, the threat feed behind the block.

Blocklists and email authentication

A listing is one reason mail lands in spam. Missing or broken SPF, DKIM and DMARC records are another, and the daily reputation check doesn't cover them. SPF, DKIM and DMARC explained walks through all three, and the free DMARC checker shows what your domain publishes today.

On every plan

The check runs once a day on every verified domain, on every plan. Alerts go to email, Slack, Telegram or a webhook.

Which plan fits depends mostly on how many domains you have. Free covers one verified domain with email alerts, which is enough for a single product or store. Founder, at $19 a month, covers five domains and adds Slack and Telegram, which suits a business with a main domain plus a separate sending domain, or a few small products. Pro, at $39 a month, covers 50 domains and adds the signed webhook, which is what agencies looking after many client domains usually need. The pricing page has the full comparison.

To check a domain now without signing up, try the free domain health check or mail health check. For a quick look at the lists alone, use the blacklist checker.