Is this really from you?Every time an email lands, the receiving server asks one quiet question: is this actually from who it says it's from? SPF is one of the tools it uses to answer that. Let's unpack it.
⬡ auth-flow, an envelope arrives at a mailbox, a question mark hovers over it, "verify sender?"SPF stands for Sender Policy Framework. In plain words, it's a little record you publish in your DNS that lists which servers are allowed to send email for your domain. You set it once, and from then on, every receiving server can check it.
⬡ record-cards, a card labeled "DNS · TXT record" holding v=spf1 include:_spf.deepcurrent.io -allHere's the practical version. Someone sends a message using your domain, say deepcurrent.io. The receiving server looks up your DNS, finds your SPF record, and checks one thing: is the sending server's IP address on your approved list? If it is, the message passes SPF. If it isn't, it fails.
⬡ auth-flow, sending IP checked against the approved list, green PASS if it matches, red FAIL if it doesn'tIf this is already making sense, subscribe. We're walking through all of email authentication, one question at a time.
⬡ title-card, "Subscribe · the authentication series"Now, an SPF fail doesn't automatically mean your email gets blocked. What happens next depends on your DMARC policy and the receiving server's own rules. But failing SPF is a mark against your message, and marks add up when they land next to other weak signals.
⬡ gauge-meter, a trust needle nudges down on fail, not slammed to zeroSPF doesn't work alone. It's part of a trio. SPF verifies the sending server. DKIM signs the message content so it can't be tampered with. DMARC ties them together and tells receivers what to do when a check fails. Each one gets its own video, linked below. For now, just know SPF is the "which servers are allowed" piece.
⬡ record-cards, three cards: SPF "authorized servers" · DKIM "signed content" · DMARC "the rulebook"So SPF is your domain's guest list. It tells the internet which servers are allowed to speak for you. It proves identity. It does not, by itself, guarantee the inbox, that's a separate story. But without it, you're a stranger at the door.
⬡ title-card, "SPF = your domain's guest list of allowed servers"Want to know why SPF had to be invented in the first place? That's the next video. And subscribe if you want the whole authentication playbook.
⬡ end-card, Subscribe + Next: "What problem was SPF created to solve?" (003.001.002)What is SPF? SPF (Sender Policy Framework) is a DNS record that lists which servers are allowed to send email for your domain. In under three minutes: how a receiving server looks up your SPF record and checks the sending IP against your approved list, what an SPF fail actually means (it's a signal, not an automatic block), and how SPF fits alongside DKIM and DMARC as the email authentication trio.
Chapters:
0:00 Is this really from you?
0:20 What SPF is, in one line
0:45 How the check runs
1:20 What a fail actually means
1:50 SPF, DKIM, and DMARC
Concepts in this video:
SPF → /emailalmanac/authentication/spf/what-is-spf
DKIM → /emailalmanac/authentication/dkim/what-is-dkim
DMARC → /emailalmanac/authentication/dmarc/what-is-dmarc
Check your SPF record free (30 seconds, no signup): reviewmyemails.com/tools/spf-checker
Full written guide → reviewmyemails.com/emailalmanac/authentication/spf/what-is-spf
#email #SPF #deliverability