SPF (Sender Policy Framework) is a TXT record that lists which servers are authorized to send mail for a domain. Receiving mail systems check the SPF record during delivery and may reject or quarantine mail from unlisted senders.

SPF Record Check for microsoft.com

SPF record looks good

Raw record

v=spf1 include:_spf-a.microsoft.com include:_spf-b.microsoft.com include:_spf-c.microsoft.com include:_spf-ssg-a.msft.net include:_spf1-meo.microsoft.com -all

DNS lookups: 7 of 10

The record above is parsed for the policy mechanism (~all soft-fail vs -all hard-fail vs ?all neutral) and the list of allowed senders. SPF has a 10-DNS-lookup hard limit per RFC 7208 — the count above shows where this domain stands.

A missing or syntactically invalid record means receivers fall back to local heuristics — often unfavorable. Hard-fail (-all) gives the strongest guarantee but breaks legitimate forwarding; soft-fail (~all) is the common production compromise. If lookups approach the 10 limit, consolidate include: chains.