How do MX records determine where mail is delivered?

A TXT record stores text information in DNS that other servers can query. For email, TXT records are essential for authentication.

Email uses for TXT records:

SPF (Sender Policy Framework): Lists which servers are authorized to send email for your domain. Stored as a TXT record starting with "v=spf1".

DKIM public keys: Published as TXT records so receiving servers can verify your email signatures.

DMARC policy: Your domain's policy for handling authentication failures. Also a TXT record.

Domain verification: Services like Google or your ESP often verify domain ownership by asking you to add a specific TXT record.

Example TXT records:

SPF: v=spf1 include:_spf.google.com ~all
DMARC: v=DMARC1; p=quarantine; rua=mailto:dmarc@yourdomain.com
DKIM: (long cryptographic key string)

Managing TXT records: Access through your DNS provider or domain registrar. Be careful with syntax, one misplaced character can break authentication.

If DNS is the phone book of the internet, TXT records are the notes scribbled in the margins. They don't route traffic, but they communicate crucial information about identity and policy.