What it means
SPF, DKIM and DMARC are three DNS records that prove an email comes from the domain it claims. SPF (Sender Policy Framework) lists the servers allowed to send for your domain. DKIM (DomainKeys Identified Mail) adds a signature that shows the message was not changed on the way.
DMARC (Domain-based Message Authentication, Reporting and Conformance) tells receiving servers what to do when a message fails those checks, and sends you reports. Since February 2024, Google and Yahoo have required all three from bulk senders.
How we use it
Every sending domain we set up passes SPF, DKIM and DMARC before it sends a single email. The records go in when the secondary domains are bought, alongside the inboxes, and before warm-up starts. A domain that fails any of the three is fixed before it sends, never worked around.
Getting them right once is not the end of it. A new sending tool, a new mailbox provider or a DNS change can break a record, so the three need checking again whenever the setup changes.
The step-by-step setup is in our cold email deliverability checklist.