A DNS-based blocklist (DNSBL, also called an RBL) is a list of IP addresses with a poor sending reputation. Mail servers query these lists to decide whether to accept mail. Being listed can cause your email to be rejected or marked as spam.

Why might my IP be listed?

Common reasons: a compromised account sending spam, a misconfigured mail server, shared hosting with a bad neighbour, or a past incident. Each blocklist publishes a delisting process.

Can I monitor this automatically?

Yes — Uptimeify’s DNSBL monitoring checks your IPs against blocklists on a schedule and alerts you the moment one gets listed, so you can act before deliverability suffers.

Blacklist Check

DNSBL / Blacklist Check

Check a public IP address (IPv4 or IPv6) against the blocklists our DNSBL monitoring uses — with the reason and a delisting link for every listing.

Enter a public IP address to check.

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Frequently asked questions about DNSBL / Blacklist Check

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