SPF, DKIM, DMARC, and MX Records Explained

MX controls where mail is delivered

MX records tell other mail servers which host accepts email for a domain. Lower priority numbers are tried first. If MX points to an old provider, mail can continue going to the wrong place even when the website is working correctly.

TXT records prove and protect sending

SPF is usually stored as a TXT record and lists which servers are allowed to send mail for a domain. DKIM uses a TXT record under a selector hostname to publish a public key. DMARC uses a TXT record at _dmarc.example.com to tell receivers how to handle mail that fails SPF or DKIM alignment.

Common mistakes

• Multiple SPF records on the same hostname instead of one combined SPF policy.
• Forgotten include values after changing email providers.
• DKIM selector published under the wrong hostname.
• DMARC policy enabled before legitimate senders are aligned.
• Old MX records left behind after a migration.

Practical review process

Check MX first to confirm mail delivery, then TXT records for SPF, DKIM, and DMARC. Compare results with the exact records requested by your email provider. If delivery is already broken, avoid deleting records until you know which system still sends mail for the domain.

Use MX Record Lookup and TXT Record Lookup to collect public DNS evidence before making changes.