Check the TXT records for any domain, including SPF and verification entries.
TXT records store text that other systems read. They power email authentication like SPF and DMARC, prove domain ownership for many services, and carry assorted configuration values.
For email security specifically, use the SPF & DMARC checker. See also the DNS lookup tool.
A TXT record holds free-form text in DNS. It's widely used for email security (SPF and DMARC), domain ownership verification, and other service configuration.
Common ones include v=spf1 records that authorise mail senders, domain-verification strings from services like Google, and DMARC policies under _dmarc.yourdomain.
Domains often have several, one per service or policy. That's normal. Each is read independently by whatever service it's meant for.