What is SPF Record?
A DNS TXT entry naming the mail servers allowed to send for a domain, checked against the envelope sender. Receivers distrust or reject mail from unlisted servers, so publishing SPF is step one of authentication.
Example
A BYOB project sends receipts from its own domain through a mail provider. Publishing the provider’s sending hosts in one SPF TXT record tells receivers that matching mail is legitimate instead of spoofed.
What people get wrong
Stacking multiple SPF records or piling on includes until lookups fail. One record, minimal includes, then validate with a checker before campaigns start.
Frequently asked questions
Why does SPF alone not stop all spoofing?
SPF checks the envelope sender, which recipients never see. Pair it with DKIM and a DMARC policy so the visible From domain carries the authentication result.
Related terms
DKIM Signing
Cryptographic email signing where the sender attaches a signature header verified against a DNS-published public key. Passing DKIM proves the message survived transit unmodified and truly came from the domain holder.
DMARC Policy
A DNS rule telling receivers how to treat mail that fails SPF and DKIM alignment: monitor, quarantine, or reject. Published reports then reveal exactly who sends as your domain, legitimate or not.
Return-Path Alignment
Matching the envelope sender domain used for SPF with the visible From domain that recipients see. Aligned domains let inbox providers credit authentication to the brand instead of the sending platform.
Sender Identity
The verified domain or address a provider is permitted to send from, proven through DNS records. BYOB projects verify sending domains before campaigns so transactional mail leaves from a trusted name.
DNS Verification (TXT)
Proving domain ownership by publishing a provider-issued token as a DNS TXT record. BYOB custom-domain and sender setup both use this challenge before activating routing or sending.
Complaint Feedback Loop
A mailbox-provider channel reporting when recipients mark mail as spam, so senders can suppress complainers immediately. Ignoring complaints burns sender reputation far faster than any single campaign gains.