SPF, DKIM and DMARC: what each one does
SPF, DKIM and DMARC are three DNS records that prove an email sent with your domain name really comes from you. SPF lists the servers allowed to send, DKIM signs each message, and DMARC tells the recipient what to do when the check fails — and sends you reports. Since 1 February 2024, Gmail has required at least one of the first two from every sender.