SPF (TXT)
Lists authorized senders for your domain. Required for SMTPServer domain verification.
DNS lookup — inspect records for email authentication.
Query TXT, CNAME, A, and other DNS records for any hostname. Use when verifying SPF, DKIM, and tracking CNAME values from your SMTPServer dashboard.
Which DNS records matter for email?
DKIM (TXT)
Cryptographic signature proving messages were sent by you. Usually on a selector subdomain.
Tracking CNAME
Branded click/open tracking domain — see click tracking.