IPTools UK

Email DNS Checker

Check a domain's MX, SPF and DMARC records, and DKIM for a given selector, with plain-English explanations.

About this tool

Email authentication relies on several independent DNS records working together. This tool checks MX (where mail is delivered), SPF (who may send on the domain's behalf), DMARC (what receivers should do with unauthenticated mail) and, if you provide a selector, DKIM (message signing). Each result includes a plain-English explanation of common misconfigurations — not just a pass/fail.

How to use this tool

  1. Enter a domain name, e.g. example.com.
  2. Optionally, enter your mail provider's DKIM selector if you know it.
  3. Select "Check". The URL updates with your query, so results can be bookmarked or shared.
No guarantees

This tool checks DNS configuration only. It cannot confirm mail delivery, spam classification, or sending reputation.

Frequently asked questions

What do SPF, DKIM and DMARC do?
SPF lists which mail servers are authorised to send email for a domain. DKIM cryptographically signs outgoing messages so receivers can verify they weren't altered in transit. DMARC tells receiving servers what to do when a message fails SPF and/or DKIM checks, and can request reports.
Why do I need to provide a DKIM selector?
DKIM public keys are published at a DNS name that includes a "selector" chosen by your mail provider (e.g. "google" or "selector1"), and there is no reliable way to discover it by querying DNS alone. Check your mail provider's documentation for the selector they use.
Does a good result here guarantee my email won't be marked as spam?
No. These checks confirm your domain's authentication records are present and well-formed, which is an important part of deliverability — but spam filtering also considers sending reputation, content, volume and many other factors outside DNS.

DNS Lookup

Query A, AAAA, CNAME, MX, TXT, NS, SOA and CAA records for any domain using DNS-over-HTTPS, with full TTL and record detail.

WHOIS Lookup

Look up registration data for a domain, IPv4/IPv6 address or ASN using RDAP, the structured successor to legacy WHOIS.

Reverse DNS

Look up the PTR record for an IPv4 or IPv6 address to find its reverse hostname.