Free Domain Health Checker

Understanding Domain Email Health

Email deliverability depends on more than just writing a great message. Before your email even reaches the inbox, receiving mail servers check your domain's authentication records to decide whether to accept, quarantine, or reject your message. A properly configured domain is the foundation of successful email outreach, marketing, and transactional communication.

Our free domain health checker performs real-time DNS lookups to verify the four pillars of email authentication: MX records, SPF, DKIM, and DMARC. Each plays a critical role in establishing your domain's trustworthiness with email providers like Gmail, Outlook, and Yahoo Mail.

MX Records: Your Email's Front Door

MX (Mail Exchange) records tell the internet which servers handle email for your domain. Without properly configured MX records, your domain cannot receive email at all. Multiple MX records with priority values provide redundancy — if your primary mail server is down, email routes to the backup server automatically.

SPF: Authorizing Your Senders

SPF (Sender Policy Framework) is a DNS TXT record that lists which IP addresses and servers are authorized to send email on behalf of your domain. When a receiving server gets an email claiming to be from your domain, it checks the SPF record to verify the sending server is authorized. A missing or misconfigured SPF record is one of the most common reasons emails land in spam. Best practice is to include all your sending services (Google Workspace, Brevo, SendGrid, etc.) and end with -all or ~all to reject unauthorized senders.

DKIM: Signing Your Emails

DKIM (DomainKeys Identified Mail) adds a cryptographic signature to every outgoing email. The receiving server retrieves your public key from DNS and uses it to verify the signature, confirming that the email content has not been altered in transit and truly originated from your domain. Most email providers generate DKIM keys during setup — you just need to publish the DNS record they provide.

DMARC: The Policy Layer

DMARC (Domain-based Message Authentication, Reporting and Conformance) ties SPF and DKIM together with a policy that tells receiving servers what to do when authentication fails. A DMARC policy of p=none only monitors, p=quarantine sends failures to spam, and p=reject blocks them entirely. DMARC also enables reporting, so you can see who is sending email on behalf of your domain and catch spoofing attempts.

Why Regular Checks Matter

DNS records can break silently. Switching email providers, adding marketing tools, or even routine DNS changes can inadvertently remove or overwrite critical authentication records. Regular domain health checks help you catch issues before they impact your deliverability. We recommend checking your domain health monthly and after every DNS or email infrastructure change.

Domain Health Best Practices

• Configure SPF, DKIM, and DMARC for every domain you send email from
• Use DMARC reporting to monitor unauthorized use of your domain
• Keep your SPF record under 10 DNS lookups to avoid permerror failures
• Start DMARC with p=none, then gradually move to p=quarantine and p=reject
• Re-check domain health after every DNS change or email provider migration