Email Domain Checker

Check MX delivery records and SPF, DMARC, and DKIM authentication configuration from multiple global Agent locations.

Check email DNS configuration

If no DKIM selector is provided, NetOpsKit checks a bounded list of common selectors. A provider-specific selector gives a definitive DKIM lookup.

What this Email Domain Checker does

The tool treats mail routing and sender authentication as one operational configuration. Every Agent checks MX records for mail delivery, the root-domain SPF policy, the DMARC policy at _dmarc, and selector-specific DKIM public keys.

MX records and mail delivery

MX records identify the servers that receive email for a domain. Lower preference values are tried first. A Null MX record explicitly states that the domain does not accept email, while a missing MX can cause senders to fall back to the domain's address record.

SPF, DKIM, and DMARC

SPF authorizes sending infrastructure. DKIM attaches a cryptographic signature associated with a selector. DMARC evaluates alignment with the visible From domain and publishes a monitoring, quarantine, or reject policy.

Understanding warnings

Multiple SPF or DMARC policy records are invalid. SPF +all is unsafe. DMARC p=none is a monitoring policy rather than enforcement. A DKIM record not found during automatic discovery does not prove that DKIM is absent because selectors cannot be universally enumerated.

Why global checks are useful

Mail DNS changes are cached according to TTL. Comparing Agent locations helps distinguish a persistent configuration error from temporary propagation or resolver-cache differences.

Frequently asked questions

What does the Email Domain Checker test?

It checks mail exchanger records, the domain's SPF policy, the DMARC policy under _dmarc, and DKIM public keys for either the selector you provide or a bounded list of common selectors.

Does a passing result guarantee email delivery?

No. DNS authentication is only one part of delivery. Sender reputation, message content, reverse DNS, IP blocklists, rate limits, and recipient policy also affect acceptance.

Why can DKIM not always be detected from only a domain?

DKIM records are stored under selector-specific names and DNS does not provide a standard selector directory. Enter the selector used by your mail provider for an authoritative check.

What does DMARC p=none mean?

It requests monitoring and reports but does not ask receivers to quarantine or reject messages that fail alignment. It is useful during rollout but provides less enforcement than quarantine or reject.

Why do results differ between locations?

DNS caches can hold different versions until TTL expiry. A recent mail configuration change may therefore appear at some Agent locations before others.