Guides · updated 2026-09-06

How to Check If Your IP or Domain Is Blacklisted

A DNSBL (a DNS-based blocklist, sometimes called an RBL) is a published list of IPs or domains with a bad sending reputation. Mail servers query these lists in real time and reject or spam-folder anything on them. Here is how to see where you stand.

Run a free blacklist check

Fastest route is to check your IP or domain against many blocklists in one shot. The free blacklist checker takes an IP (your sending server, say) or a domain and queries Spamhaus plus a curated set of DNSBLs — and while it is at it, checks your SSL, domain expiry, and SPF/DMARC in the same pass.

How to read the result

• Listed — you are on one or more blocklists, and it is hurting delivery right now. Here is how to get delisted.
• Clean — nothing found on any active list at the moment.
• Unknown / error — a lookup failed, which is not the same as "clean." Try again in a bit. Any checker worth trusting will never pass off a failed query as clean.

Why a one-time check is not enough

Listings arrive with no warning. A compromised account, a bad neighbor on shared hosting, an unexpected volume spike — any of them can put you on a list overnight. And by the time customers start reporting bounced mail, you have already burned days of deliverability.

Monitor continuously instead

Deliveradar rechecks your IPs and domains on a schedule and fires an alert to email and Telegram the second you show up on a list — so you catch it before it costs you anything. Start monitoring free.