Why check SPF, DKIM, and DMARC together?

DMARC depends on SPF or DKIM alignment, so checking all three together helps identify whether the domain has a complete email authentication setup.

Do I need a DKIM selector?

A DKIM selector is required for a DKIM lookup, but SPF and DMARC can still be checked without one.

Can these checks guarantee delivery?

No. Correct authentication is important, but delivery also depends on content, reputation, sending practices, 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 is used to publish which systems are allowed to send mail for a domain, but SPF records can become invalid through syntax problems, too many DNS lookups, missing include targets, or duplicate records.

DKIM

DKIM stands for DomainKeys Identified Mail. It relies on selectors and public keys in DNS so receiving servers can validate signed messages, but it often goes wrong when the selector is missing, rotated badly, malformed, or still uses a weak RSA key size.

DMARC

DMARC stands for Domain-based Message Authentication, Reporting, and Conformance. It sits on top of SPF and DKIM, using alignment and policy tags such as p, rua, adkim, and aspf to control monitoring and enforcement.

Why Problems Matter

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

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 records with syntax, lookup-limit, or include problems
DKIM selectors that are missing, duplicated, or malformed
DMARC records with invalid policies or reporting tags
DMARC enforcement while SPF or DKIM still has issues
Missing DKIM selector when a DKIM check is requested

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.