What are SPF, DKIM and DMARC?
Nicklas Segatz Mortensen · Growth Hacker · Fractional CMO · Meta Ads Nerd · 8 July 2026 · 3 min.
Definition
SPF, DKIM and DMARC are email authentication standards that let the recipient's mail server verify that an email really was sent from the domain it claims — and therefore isn't spoofed.
Also called: SPF, DKIM, DMARC, Email authentication
Sådan virker det
SPF, DKIM og DMARC er de tekniske standarder, der beviser, at dine mails faktisk kommer fra dig. Uden korrekt opsætning ser indbakke-udbyderne dig som mulig spam eller svindel. Med dem på plads stiger både deliverability og tillid.
01Proof that you are who you say you are
SPF specifies which servers are allowed to send on behalf of your domain. DKIM attaches a cryptographic signature to every email, so the recipient can verify the content wasn't altered in transit and that it came from you. DMARC ties the two together and tells the recipient what to do if an email fails the check.
Without proper setup, inbox providers treat you with suspicion — your emails may land in spam or get rejected because they can't confirm the sender. With SPF, DKIM and DMARC in place, both deliverability and the trust your domain enjoys go up. It's basic infrastructure, not a nice-to-have.
Frequently asked questions
Are SPF, DKIM and DMARC necessary?+
Yes. Without them, inbox providers see your emails as possible spam or spoofing, which hurts deliverability. Major providers increasingly require proper authentication to deliver bulk email at all.
Who sets up SPF, DKIM and DMARC?+
It's done in your DNS settings and typically configured alongside your email platform (like Klaviyo). It's a one-time setup with a big impact on whether your emails arrive — and worth checking if deliverability is struggling.
Related terms
Glossary
What is deliverability?
Deliverability is the share of your sent emails that actually land in the recipient's inbox rather than in spam or getting rejected entirely.
Read the entry →Glossary
What is a sunset flow?
A sunset flow gradually steps profiles that haven't engaged over a longer period down and eventually out of active sending — to protect your sender reputation.
Read the entry →Glossary
What is double opt-in?
Double opt-in is a sign-up method where a new contact must confirm their subscription via a link in an email before they're added to your active list.
Read the entry →
Nicklas Segatz Mortensen
Growth Hacker · Fractional CMO · Meta Ads Nerd at Oaksmond
Growth hacker and fractional CMO with 10+ years' experience and hundreds of millions in managed ad spend behind him. Background from larger Danish and international scale-ups, and from the agency world.
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