What is SPF?
Sender Policy Framework — lists which servers may send mail for your domain.
Written by the SkyQon engineering team · Last verified 4 August 2026
Why it matters
SPF is the first thing a receiving mail server checks. Without it, anyone can put your domain in the From address and most inboxes will accept the message. With it, you decide which servers may send on your behalf — and DMARC gains something to enforce.
The standard
RFC 7208 (2014), which replaced the experimental RFC 4408. SPF is published as a single DNS TXT record at the root of your domain, beginning v=spf1 and ending in an all mechanism.
Official text: RFC 7208
How it fails
Most SPF breakage goes unnoticed at first. SPF allows a maximum of ten DNS lookups, and every SaaS sender you add — invoicing, CRM, ticketing, marketing — consumes some. Cross the limit and evaluation returns permerror, which many receivers treat as no SPF at all. Ending the record in +all rather than -all or ~all has the same practical effect as publishing nothing.
Related terms
Check this on your own domain
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