Glossary
SPF: what it is and why your domain needs it
SPF (Sender Policy Framework) is an email authentication standard that lets a domain owner publish, in a DNS record, which servers are authorized to send email on the domain's behalf. Receiving servers check that record to detect spoofed senders, making SPF a baseline requirement for deliverability.
How does SPF work?
When your domain sends an email, the receiving server extracts the domain from the envelope sender and looks up its SPF record in DNS. The record is a single TXT entry listing authorized sources: your mail provider, your marketing platform, your outbound sending tool. If the connecting server's IP matches the list, the check passes; if not, the result is a soft fail or hard fail depending on how the record is configured, and the receiver factors that into its filtering decision.
Two practical limits cause most problems. First, a domain may publish only one SPF record — adding a second breaks validation entirely. Second, the standard allows a maximum of ten DNS lookups per check, and every "include" of a third-party tool consumes some of them, so records accumulated over years often fail without anyone noticing.
Why it matters in B2B
SPF is one of the three authentication pillars alongside DKIM and DMARC, and mailbox providers treat unauthenticated senders as suspect by default. For an outbound program, a broken SPF record means the campaign is losing deliverability before a single word of copy is evaluated.
Imagine a hypothetical consulting firm that adds a new sending platform for its prospecting campaigns but never updates the SPF record. The platform's messages fail authentication, replies dry up, and the team blames the messaging — when the real fault is a missing line in DNS.
In every deployment of its AI outbound systems, AVANTAI configures and verifies SPF, DKIM and DMARC on the sending domains before any sequence goes live, because authentication is infrastructure, not an afterthought.
Frequently asked questions
Is SPF alone enough to authenticate my email?
No. SPF validates the sending server, but it breaks with forwarding and does not sign the message content. It should always be combined with DKIM and DMARC; major providers such as Google and Yahoo require this combination from bulk senders.
What happens if my SPF record is wrong?
Legitimate email can be rejected or sent to spam. Common errors include exceeding the 10 DNS lookup limit, publishing multiple SPF records for one domain, or forgetting to include a sending tool. Any of these can silently undermine deliverability.
Do I need SPF on domains that never send email?
Yes. Publishing a restrictive SPF record on non-sending domains prevents third parties from spoofing them, which protects your brand and stops attackers from using your parked or secondary domains for phishing.