Why can separate checks miss the real problem?

SPF, DKIM, and DMARC are related. DMARC can fail because SPF or DKIM is missing, because alignment is wrong, or because the policy is too strict for the current sender setup.

What happens if I leave the DKIM selector blank?

The combined checker still reviews SPF and DMARC, then notes that DKIM was skipped because selector-specific DNS cannot be queried without a selector.

Can good authentication guarantee inbox delivery?

No. Authentication is a foundation, but delivery also depends on reputation, content, complaint rates, bounce handling, list quality, and recipient filtering.

AUTHPROBLEM.comEmail Authentication Analysis

About Email Authentication

Modern email authentication is built on three main DNS-backed controls: SPF, DKIM, and DMARC. Together they help domain owners declare which systems may send mail, publish signing keys, and tell receiving servers how to handle mail that fails alignment checks.

This site brings those three checks together so a domain can be reviewed in one place rather than as three separate lookups.

SPF

SPF stands for Sender Policy Framework. It publishes the mail servers and services that are allowed to send using a domain, usually through direct IP ranges and provider include mechanisms.

SPF is often where sender inventory problems show up first: old services remain authorized, new services are missing, or provider include chains push the domain close to the DNS lookup limit.

DKIM

DKIM stands for DomainKeys Identified Mail. It uses a private key in the sending platform and a public key in DNS so receivers can confirm that signed parts of the message were not altered.

DKIM problems are usually selector-specific. The domain may have good DKIM elsewhere, but a single missing selector, stale CNAME, duplicated TXT record, or weak key can affect one sender.

DMARC

DMARC stands for Domain-based Message Authentication, Reporting, and Conformance. It checks whether SPF or DKIM aligns with the visible From domain and then applies the published policy.

DMARC is where the pieces meet. A strict policy can be useful, but only after legitimate senders are passing SPF or DKIM alignment reliably.

Why Problems Matter

If any layer is missing, invalid, or misaligned, legitimate email may be filtered, rejected, or lose the reporting and policy protection needed to monitor spoofing and delivery health.

A combined check is useful because the visible symptom is often not the root cause: a DMARC warning may really be a DKIM selector problem, or an SPF pass may still fail DMARC because the domains do not align.

This site is intended as a troubleshooting and analysis aid. Results should always be independently checked before any production DNS or email changes are made.

Relevant RFCs

These specifications define the core standards behind the checks on this site.

RFC 7208 - Sender Policy Framework (SPF) for Authorizing Use of Domains in Email, Version 1
RFC 6376 - DomainKeys Identified Mail (DKIM) Signatures
RFC 8301 - Cryptographic Algorithm and Key Usage Update to DKIM
RFC 8463 - A New Cryptographic Signature Method for DKIM
RFC 7489 - Domain-based Message Authentication, Reporting, and Conformance (DMARC)
RFC 8616 - Email Authentication for Internationalized Mail

Common Problems Checked

SPF record consumes too many DNS lookups or misses a sender
DKIM selector is absent, duplicated, delegated incorrectly, or weak
DMARC policy is missing, malformed, or too strict for the current setup
DMARC enforcement may reject legitimate mail because SPF or DKIM is not aligned
Combined result shows where one layer depends on another

Improve Delivery

This site lets you check your SPF, DKIM, and DMARC configuration. Correct sender authentication is very important, but it is also only a starting point. For more information and practical tips on improving email delivery, visit Outgoing.email.

Questions or Issues

If you spot something that looks wrong, have a suggestion, or want to share details of a problem with one of the checks, please contact us.