SPF lists the servers allowed to send mail for your domain. DKIM adds a digital signature that proves the message was not altered. DMARC tells receivers what to do when SPF or DKIM checks fail and sends reports back to the domain owner.
Why it matters
Mailbox providers increasingly expect these records, especially for bulk senders. Without them, legitimate mail is more likely to be filtered and others can more easily spoof your domain.
Common pitfalls and tips
Setup is done in your domain’s DNS, usually with help from your email provider. Test with a free checker after changes, and review DMARC reports before moving to a stricter policy.
Example
A company sets up SPF and DKIM for its sending platform, then publishes a DMARC policy that starts in monitoring mode. Reports show which services send mail, and the policy is tightened later.