Free Email Authentication Tools

DMARC (Domain-based Message Authentication, Reporting, and Conformance) is an email authentication protocol that protects your domain from unauthorized use, including phishing and email spoofing. It works by telling receiving mail servers what to do when an email fails SPF or DKIM checks. Without DMARC, attackers can send emails that appear to come from your domain, damaging your brand reputation and putting your customers at risk.

SPF (Sender Policy Framework) is a DNS TXT record that specifies which mail servers are authorized to send email on behalf of your domain. When an email arrives, the receiving server checks the SPF record to verify the sending server is authorized. SPF has a limit of 10 DNS lookups, and exceeding this limit causes a permanent error (permerror) that can break email delivery.

DKIM (DomainKeys Identified Mail) adds a cryptographic signature to your emails, allowing receivers to verify that the email was sent by an authorized sender and wasn't altered in transit. The signature is created using a private key (kept secret) and verified using a public key published in your DNS. DKIM helps prevent email tampering and improves deliverability.

Yes, all our email authentication checker tools are completely free to use with no registration required. You can check as many domains as you need, as often as you like. For ongoing monitoring, alerts, and detailed analytics, consider signing up for a free Verkh account.

These three protocols form a layered email authentication system. SPF verifies the sending server is authorized, DKIM verifies the message hasn't been tampered with, and DMARC ties them together with a policy that tells receivers what to do when checks fail. For DMARC to pass, either SPF or DKIM must pass AND be aligned with the From domain.

DMARC alignment means the domain in the From header matches the domain used for SPF or DKIM authentication. There are two alignment modes: strict (exact match required) and relaxed (organizational domain match allowed). For example, with relaxed alignment, mail.example.com would align with example.com.

Start with p=none to monitor without affecting email delivery. This lets you see who's sending as your domain and identify legitimate senders. Once you've authorized all legitimate sources and fixed authentication issues, move to p=quarantine (suspicious emails go to spam) and eventually p=reject (unauthorized emails are blocked entirely).

Failed email authentication is one of the most common causes of emails landing in spam. Use our tools to check if your SPF, DKIM, and DMARC records are properly configured. Other factors include sender reputation, content quality, and recipient engagement. Proper authentication is the foundation for good deliverability.