Glossary

SPF Record — What It Is and How to Fix It

SPF is a TXT record that answers: “which IPs may send mail as my domain?” Receivers check it before they trust the From: header. Fail the check and you often land in spam or bounce — even when the mail is real.

How SPF Records Work

You publish IPs and includes in DNS. The receiver compares the connecting server to that list. They’ll mark pass, fail, softfail, or neutral — and DMARC may still fail if you don’t align later.

The SPF 10-Lookup Limit

SPF only gets 10 DNS lookups. Every include:, a:, mx: costs one. Blow past 10 and you hit PermError — many receivers treat that like “no SPF,” so legit mail dies.

Common SPF Problems

• Too many include: chains (nested ESPs eat lookups fast)
• Two TXT records that both start with v=spf1 — that’s invalid
• Using +all (allows anyone — don’t)
• Forget to add your ESP’s include

How to Check Your SPF Record

Open DNS Preflight, expand the SPF tree, and see exactly where lookups go. We also show fixes you can paste.