Email Blacklist Checker (Free)

Check if your mail server IPs are listed on major email blacklists (DNSBLs). Fast, read-only, and safe.

Check my domainHow it works

Read-only checks · No email sending · Works even if SPF/DMARC are correct

How it works

Most email blacklists (DNSBLs) list mail server IP addresses, not domains. InboxReady resolves your domain's mail servers and checks those IPs against major blocklists.

  • We look up your domain’s MX (mail server) records.
  • We resolve the mail servers to IP addresses.
  • We check those IPs against major DNS blocklists.

These checks are read-only and safe. We never send email on your behalf or modify DNS records for your domain.

If your emails aren't sending at all (not just landing in spam), see: SMTP AUTH migration (Exchange Online).

What we check

InboxReady currently checks your mail server IPs against a focused set of widely used email blacklists:

  • Spamhaus (zen)
  • Spamcop
  • Barracuda
  • SORBS
  • PSBL

We keep the list intentionally small and reputable to reduce noise and false positives.

FAQ

Why can SPF/DMARC pass but deliverability still fails?

SPF and DMARC confirm that you're authorised to send from a domain and that alignment rules are met. Blacklists look at the mail server IPs actually delivering your mail. Those IPs can be listed for past behaviour even when SPF/DMARC are configured correctly.

What if I'm using a shared ESP?

Many ESPs send from shared IP pools. If a shared IP shows up on a blacklist, you'll typically need to contact your provider with the IP and list name. They can confirm impact, move you to a different pool, or handle delisting on their side.

Do you check IPv6?

Today's blacklist checker focuses on IPv4 mail server IPs resolved from your MX records. IPv6-only configurations may not be fully covered in this version.

Blacklists typically list IPs, not domains. If you use a shared ESP IP, contact your provider with the IP and list name.