Check SPF before hidden DNS errors hurt outbound.
Paste one or more sending domains. Folderly Lens checks SPF multiple records, lookup limits, duplicate includes, null records, DMARC, MX, and blacklist exposure so you see whether to retire, fix, or keep each domain.
Why SPF breaks cold-email estates
Multiple SPF records
More than one SPF TXT record makes SPF evaluation fail even when each record looks reasonable alone.
Lookup budget errors
Too many include, redirect, a, mx, ptr, or exists mechanisms can push SPF over the RFC limit of 10 DNS lookups.
Duplicate or null SPF
Duplicate includes waste lookup budget, while a bare v=spf1 record authorizes no sender.
How to use the SPF result
If SPF is invalid
Merge multiple SPF records, replace null records, and keep only one active SPF TXT record per domain.
If lookups are high
Remove unused includes, flatten stable senders where appropriate, or split senders by subdomain before scaling volume.
If SPF is clean
Keep the domain only if DMARC, MX, and blacklist signals are also clean. A clean SPF record does not rescue a listed or unauthenticated estate.
SPF checker FAQ
What does Lens test?
Lens checks SPF existence, multiple records, null values, duplicate includes, and DNS lookup budget. The full verdict also considers DMARC, MX, and DNSBL exposure.
Do you need inbox access?
No. SPF lives in public DNS. Folderly Lens does not require sequencer, mailbox, or sender-platform credentials.
Can SPF prove inbox placement?
No. SPF is a structural trust signal. Inbox placement needs separate seed or mailbox-provider data; this page focuses on public infrastructure risk.