Blacklist check
Check whether a domain's IP address is on blacklists such as Spamhaus, Barracuda and SpamCop.
About blacklist check
What it is
A blocklist (DNSBL/RBL) is a list of IP addresses reported for sending spam. Receiving servers check against lists such as Spamhaus before they let mail in.
Why it matters
If your server ends up on a blocklist, your mail is blocked or marked as spam by recipients, often without you noticing until customers reach out. That harms both delivery and trust.
Tips
- If you are listed, find out the cause (a compromised account, a misconfiguration) before requesting delisting.
- Protect outgoing mail with SPF, DKIM and DMARC to reduce the risk.
- Monitor continuously, a listing can happen at any time.
Common questions
What is Spamhaus?
One of the most widely used providers of blocklists covering IP addresses linked to spam and abuse.
How do I remove a domain from a blocklist?
First fix the root cause, then request delisting via the blocklist's website, for example spamhaus.org.
More lookups
MX lookup
See which servers receive mail for a domain, and which provider handles it.
SPF check
Check whether a domain has an SPF record and how strictly it rejects spoofed mail.
DMARC check
See whether a domain has DMARC and which policy it uses against spoofed mail.
DKIM check
Look for DKIM signing on a domain using the most common selectors.
DNSSEC check
See whether a domain is protected with DNSSEC, that is, whether its DNS answers are signed.
TXT lookup
List all TXT records for a domain, including SPF, verifications and more.
NS lookup
See which name servers control a domain's DNS.
A/AAAA lookup
See which IP addresses a domain points to, both IPv4 (A) and IPv6 (AAAA).
CNAME lookup
See whether a domain is an alias that points on to another domain.
SOA lookup
See the zone's core data: primary name server, contact and serial number.
CAA lookup
See which certificate authorities are allowed to issue certificates for the domain.
Reverse DNS (PTR)
Look up which host name a domain's IP address points back to.
MTA-STS
See whether a domain requires encrypted mail delivery via MTA-STS.
TLS-RPT
See whether a domain receives reports about failed encrypted mail delivery.
BIMI
See whether a domain publishes a logo that can be shown in the recipient's inbox.
SSL certificate
Check a domain's TLS certificate: issuer, validity and expiry.
Whois
See who owns a domain, when it was registered and when it expires.
HTTP security headers
Check whether a domain's website sets important security headers.