The most important use of TXT records is email authentication — preventing email spoofing and phishing:
- SPF (Sender Policy Framework): A TXT record listing which mail servers are authorized to send email for your domain. Receiving servers check SPF to verify the sender
- DKIM (DomainKeys Identified Mail): A TXT record containing a public key used to verify that email messages were signed by the domain's mail server and haven't been modified in transit
- DMARC (Domain-based Message Authentication): A TXT record that tells receiving servers what to do when emails fail SPF or DKIM checks — quarantine, reject, or report
Together, SPF, DKIM, and DMARC form a defense against email spoofing — a critical complement to DNS security that protects against phishing attacks.