SPF vs DKIM vs DMARC: what each protocol does
If you need better inbox placement, these are the three technical foundations you cannot skip.
SPF: sender authorization
SPF tells receiving servers which hosts are allowed to send for your domain. It helps block unauthorized senders and supports DMARC decisions.
DKIM: message integrity
DKIM adds a cryptographic signature to outgoing mail. Receivers verify that the message was not altered and was sent through an approved system.
DMARC: policy and alignment
DMARC links SPF and DKIM to your visible From domain and sets policy instructions (none, quarantine, reject).
Implementation order
- Inventory all legitimate senders.
- Deploy SPF with clean include chains.
- Enable DKIM signing for every sender.
- Publish DMARC with monitoring mode.
- Move to enforcement once alignment is stable.