MX records tell the internet where to deliver email for a domain. Without valid MX records, a domain cannot receive any email — messages bounce back to the sender.

SPF (Sender Policy Framework) is a TXT record that lists which mail servers are authorized to send email on behalf of your domain. It prevents spoofing and helps your emails pass spam filters.

DKIM (DomainKeys Identified Mail) adds a cryptographic signature to outgoing emails. Receivers verify the signature by looking up a public key in DNS, ensuring the email wasn't tampered with in transit.

DMARC (Domain-based Message Authentication, Reporting & Conformance) ties SPF and DKIM together with a policy — none (monitor only), quarantine (spam folder), or reject (bounce). It tells receivers what to do when authentication fails.

This tool checks all four — MX, SPF, DKIM, and DMARC — so you can quickly see if a domain is properly configured for sending and receiving email.