The plain-English version
Your domain is part of your business identity.
When an email message says it is from your business, receiving mail systems need signals that help them judge whether it is genuinely connected to your domain. Those signals do not make phishing or spam disappear, but they can make impersonation harder to carry out and easier to spot.
The key controls are stored in DNS—the technical directory that tells the internet where a domain’s services live. DNS records deserve an inventory and careful change management. A record that looks small can affect a website, business email, or a third-party service that sends on the business’s behalf.
Three controls worth knowing
SPF
Think of SPF as a published list of the services allowed to send mail for the domain. It helps receiving systems compare a message with the sending services the business has authorized.
DKIM
DKIM adds a cryptographic signature to outgoing messages. Receiving systems can use it to check that the message is associated with the sending domain and has not been altered in transit.
DMARC
DMARC builds on SPF and DKIM. It links those checks to the visible From address, gives the domain owner reporting, and lets the owner communicate how failed checks should be handled.
Google’s current sender guidance recommends SPF, DKIM, and DMARC for sending domains, and Microsoft documents a similar SPF–DKIM–DMARC order for custom Microsoft 365 domains. These are awareness points for the business and its qualified provider to discuss, not records to self-implement.