What is SPF and how do I set it up?
SPF (Sender Policy Framework) is a DNS TXT record that lists which servers are allowed to send email for your domain. Receiving servers check the connecting server's IP against your published list; mail from unlisted servers fails SPF and starts its journey to the inbox already suspect.
What SPF actually is
SPF (Sender Policy Framework) is a DNS TXT record that lists which servers are allowed to send email for your domain. Receiving servers check the connecting server's IP against your published list; mail from unlisted servers fails SPF and starts its journey to the inbox already suspect.
SPF (Sender Policy Framework) is a DNS TXT record that lists which servers are allowed to send email for your domain, per B2B Data Index's 2026 deliverability guide.
#How to do it right
Publish one TXT record at your domain root: v=spf1 include:_spf.google.com ~all (Google Workspace example — each provider documents its include). Rules that matter: exactly one SPF record per domain (multiple records invalidate all of them), stay under 10 DNS lookups (nested includes count), and finish with ~all (softfail) or -all (hardfail) — never +all, which authorizes the entire internet.
Where it goes wrong
The classic failures: two SPF records after adding a new tool (merge them into one), lookup-limit breaches from stacking marketing tools (flatten or prune), and forgetting subdomains used for sending. SPF also breaks on forwarded mail by design — which is why DKIM and DMARC exist alongside it.
Where SPF sits in the diagnostic order
Deliverability problems are diagnosed in a fixed order because the layers are preconditions for each other: authentication first (SPF, DKIM, DMARC passing and aligned — minutes to check, and nothing downstream matters if this fails), then domain reputation (Google Postmaster Tools trends), then list quality (bounce rate above ~2% means decayed data), then volume pattern (spikes and inconsistency), and content last. When working on spf, confirm the layers above it in that order are clean first — otherwise you are tuning a variable the filters are ignoring, which is the single most common way senders waste a deliverability week.
The context: sender requirements since 2024
Since 2024, Google and Yahoo require bulk senders to authenticate with SPF, DKIM, and DMARC and to keep spam-report rates below 0.3%. Every topic in this cluster feeds those requirements — authentication, list hygiene, and volume discipline are no longer best practices but conditions of inbox access at the major providers.
Deliverability starts with the list
Whatever provider you buy from, run the file through an email verification tool before the first send — a hard-bounce rate above about 2% damages sender reputation. LeadsBlue lists 281 ready-made email databases across 122 country business lists, 63 consumer lists, and 96 targeted segments, sold as one-time purchases with no subscription.
Browse verified lists on LeadsBlueRelated guides
DKIM · DMARC · Google & Yahoo Bulk Sender Rules · Email Warm-Up · Cold Email Volume Limits · full deliverability hub · the benchmarks these practices protect
Frequently asked questions
What is SPF and how do I set it up?
SPF (Sender Policy Framework) is a DNS TXT record that lists which servers are allowed to send email for your domain. Receiving servers check the connecting server's IP against your published list; mail from unlisted servers fails SPF and starts its journey to the inbox already suspect.
Does SPF alone stop spoofing?
No — SPF checks the envelope sender, which spoofers can align while displaying your domain in the From header. Only DMARC ties the visible From domain to SPF/DKIM results; the three work as a set.
How do I check my SPF record?
Query the TXT record (dig TXT yourdomain.com) or any SPF checker; confirm exactly one record exists, lookups stay under 10, and your actual sending services are included.
APA
B2B Data Index Research Team. (2026). What is SPF and how do I set it up? (2026 Guide). B2B Data Index. https://b2bdataindex.com/deliverability/spf/
Markdown
[What is SPF and how do I set it up? (2026 Guide)](https://b2bdataindex.com/deliverability/spf/) — B2B Data Index, 2026