What is an email deliverability checker?

An email deliverability checker runs live DNS queries against your domain to verify that email authentication (SPF, DKIM, and DMARC) is set up correctly. Correct authentication is the biggest lever on emails reaching the inbox instead of the spam folder, so this is where any work on improving email deliverability starts.

Sender Policy Framework: a DNS TXT record listing which mail server IPs are authorized to send email on behalf of your domain. Receiving servers check it to detect spoofed sender email addresses before applying any spam filter rules.

DomainKeys Identified Mail: a cryptographic signature added to outgoing email that lets receiving servers verify the email content wasn't altered in transit and really came from your domain.

Domain-based Message Authentication, Reporting and Conformance: a policy record that tells receiving servers what to do with mail that fails SPF or DKIM checks (none, quarantine, or reject), plus where to send reports. DMARC also shapes how spam complaints are attributed to your domain reputation.

Why do SPF DKIM and DMARC matter together?

SPF and DKIM each authenticate mail differently. DMARC ties them together with an enforcement policy. Without DMARC, failing SPF or DKIM checks don't actually stop spoofed mail from being delivered, and your email deliverability rates can drop even when the subject line and email content are strong.

Why didn't it find my DKIM record?

DKIM selectors aren't discoverable via DNS. This check tries common selectors (google, default, selector1/2, etc.), but a non-standard selector won't show up. Check your email service's DKIM setup page for your actual selector name.

What DMARC policy should I start with?

Start with p=none to monitor without affecting delivery, then move to quarantine or reject once you've confirmed legitimate mail sources all pass. Monitor spam complaints and engagement rates through the transition.

How often should I re-check?

Any time you change email providers, add a new sending tool (marketing platform, transactional email service), or make DNS changes. Also re-run before every major email marketing campaign so you know the setup is healthy before hitting your full email list.

How do I improve open rate if authentication is already passing?

Once SPF DKIM and DMARC pass, the next levers are subject line quality, list hygiene (removing bounced email addresses), engagement rates (unsubscribes vs opens), and sending emails at a consistent cadence rather than in bursts. Authentication protects deliverability, but content and engagement decide open rate.

Does this check blacklist status?

No. This checks authentication records only (SPF/DKIM/DMARC). Blacklist and reputation monitoring needs a separate dedicated service that tracks how mail servers rate your sending IP.

Does passing all 3 guarantee inbox placement?

No. Authentication is necessary but not sufficient. Sender reputation, engagement rates, and email content also affect how emails perform, and every mail server applies its own spam filter rules on top of authentication.

Does this validate DKIM signature correctness on sent mail?

No. It checks whether a DKIM record exists at common selectors, not whether your actual outgoing mail is being signed correctly. Send a test email to a deliverability testing service to verify actual signing.

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