EMAIL DELIVERABILITY

MX and RBL checker.

Resolve a domain’s highest-priority MX mail server and check its public IPv4 address against real-time IP blocklists.

Each check covers the highest-priority MX endpoint and is limited to 5 per visitor per hour and 5 per domain per day, protecting the independent RBL operators.

What this MX RBL checker does

The tool obtains the submitted domain’s MX records, resolves the selected mail exchanger to public IP addresses and asks configured IP RBL services about those addresses. It does not perform a domain-reputation lookup, send email, test SMTP authentication or attempt to relay mail.

RBL services have different listing criteria and usage policies. A result with no listing returned only means that the configured IP services did not return a listing at the time of the query; it is not a delivery guarantee.

Related network tools

DNS Lookup

Check DNS records, name servers and mail routing for a domain.

SMTP Server Check

Check a public SMTP server’s response, ESMTP capabilities and relay policy.

WHOIS

Look up domain registrar, expiry, name server and public WHOIS details.

Ping Test

Check public-host reachability, latency and packet loss.

Frequently asked questions

Technical context and standards

What is an MX record?

An MX record identifies a host that accepts email for a domain. Lower preference numbers are tried first, subject to normal SMTP delivery behaviour.

Relevant standard: RFC 5321 — Simple Mail Transfer Protocol

How does an RBL check work?

A real-time blocklist commonly encodes a reputation query in a DNS name by reversing an IPv4 address before the RBL zone. A returned answer can indicate a source-specific listing.

Relevant standard: RFC 5782 — DNS Blacklists and Whitelists

Does a listing prove that a server sends spam?

No. Each operator applies its own policy and data sources. Treat a listing as a source-specific signal, review the operator’s reason and investigate the server before taking action.

Relevant standard: RFC 5782 — DNS Blacklists and Whitelists

Why are some RBL services not included?

Many real-time blocklist operators restrict high-volume or commercial use, or require credentials. PacketPint queries only services explicitly enabled under their applicable terms.

Relevant standard: RFC 5782 — DNS Blacklists and Whitelists