Email Blacklist Checker

Check whether an IPv4 address appears on common DNS blocklists used by mail receivers.

DNSBL lookup

Enter the IPv4 sender address from your email headers.

Check sender reputation signals

DNS blocklists are one signal mail receivers can use when deciding whether to accept or filter a message.

A listing does not always mean every inbox will block you, but it is a useful starting point when mail suddenly goes to spam.

Recommended next steps

Use the full health check when one DNS record is not enough to explain inbox placement.

Read the guides for SPF, DMARC, DKIM, and blacklist cleanup.

A practical cleanup checklist for sender IPs that appear on DNS blocklists or suddenly land in spam.

Common technical reasons legitimate email lands in spam and how to investigate them.

No. It checks a focused set of common DNSBL zones and should be combined with provider-specific postmaster tools.

This checker is for IPv4 sender addresses. Look up the sending IP from your mail headers first.