SPF (Sender Policy Framework)

A DNS record listing which servers may send email for your domain.

Receivers check the sending server against the SPF record of the envelope domain. Two rules break it silently: there must be exactly one SPF record, and evaluating it may take at most 10 DNS lookups, nested includes counted. Over 10 and SPF fails for all your mail.

Share: LinkedIn · X ·

Related terms

DKIM (DomainKeys Identified Mail): A signature on each message, checked against a public key in your DNS.
DMARC: The policy that tells receivers what to do when mail fails SPF and DKIM, and where to report.

← All terms

Free tools

Business idea validatorTen rubrics, a fixed-rule verdict and three cheap experiments. Free.Software cost estimatorYour project among 125 real products, with honest ranges.Engagement configuratorPick the work and its size, see hours, price and start date.SPF, DKIM and DMARC checkerGrade any domain’s email DNS, with records to paste.BIMI checkerRecord, DMARC, SVG Tiny PS logo and VMC or CMC, with an inbox preview.

Want the fun version? The Corporate-speak Translator has a Polish dictionary of office phrases and what they really mean. Corporate-speak dictionary (Polish) →

Need this built, fixed or reviewed?

I build and rescue products with AI coding agents under rules: AI features in production, honest estimates, email that gets delivered.

Book a free 30-min call See price and start date

How I work

Przemysław Zalewski · 15+ years shipping software

“a true bias for action” client CTO, public LinkedIn recommendation

Confidential by default. NDA is standard. I never show your project, name or screenshots without written consent, which is why this site names no clients without permission.
Your code, your accounts. Code and data stay in your repository and accounts. AI tools run with training on your data turned off, and secrets never reach a model.
A handover you can use. Every project ends with the same checklist: a README that gets it running, one architecture diagram, written decisions, CI, a runbook and a recorded walkthrough. It is done when someone outside the project can run it from the docs.
Boring technology where it counts. I pick a stack you can hire for. Anything experimental needs your yes and an exit plan.
Approach matched to your risk appetite. Prototype, product or regulated: the level decides how much autonomy the agents get and how much review and validation each change needs.
Everything checkable. Every number on my pages links to its source. My tools are free, and the idea validator skill is open source (MIT).

All principles and risk levels →