What is the difference between a DKIM selector and a domain when checking DKIM?
The DKIM selector (s=) is the label that tells verifiers which specific public key to fetch at selector._domainkey.d=domain, while the DKIM domain (d=) names the signing domain that owns the key in DNS and is the value used for DMARC alignment—verification always looks up s= under d=, but only d= participates in alignment. Context and…
