SPF, DKIM and DMARC - what are they?

There are three main steps to protect emails from spam and spoofing.

SPF

DKIM

DMARC

Together they protect your emails.  He was not quite right in the DMARC does not stop spoofing on its own.  

What it does:
SPF helps prevent spammers from sending emails on behalf of your domain.
How it works:
It lists the servers/IPs allowed to send email for your domain in your DNS. Mail servers check this list to verify legitimacy.

What it does:
DKIM ensures that an email hasn’t been tampered with during transit.
How it works:
It adds a digital signature to outgoing emails, which receiving servers can verify using a public key in your DNS.

What it does:
DMARC ties SPF and DKIM together and gives you control over how unauthenticated emails are handled.
How it works:
It tells receiving servers what to do if SPF or DKIM checks fail (e.g., quarantine or reject the email), and can send you reports.