Learn SPF
SPF authorises hosts to use a domain in the SMTP MAIL FROM or HELO identity. It does not authenticate the visible From address by itself.
Read each short explanation, work through the example, then answer a pop quiz. Every answer explains the reasoning. Incorrect answers unlock a fresh question on the same idea; the full lesson contains ten questions.
01Understand the basics
Ready to learnSender Policy Framework (SPF) lets a domain publish which hosts may use that domain for the SMTP MAIL FROM or HELO identity. Receivers evaluate mechanisms from left to right. A matching qualifier produces Pass, Fail, Softfail or Neutral. SPF alone does not authenticate the RFC5322.From address people normally see.
02Respect the DNS budget
Ready to learnSPF evaluation is limited to ten DNS-querying terms. include, a, mx, ptr, exists and redirect consume the budget when reached, including terms inside evaluated includes. ip4, ip6 and all do not. Exceeding the limit produces Permerror.
Try a different value
03Flatten with ownership
Ready to learnFlattening replaces provider includes with current IP mechanisms. It removes lookups but also removes automatic provider updates. Some mechanisms depend on live DNS or ordering and cannot be safely converted from TXT values alone.
You’ve practised all three sections.
First-attempt understanding and later practice are shown separately. Keep practising with the related tools or continue through the suggested path.
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