SPF is the list of servers allowed to send email for your domain. It lives in a single TXT record, and receiving servers check it on every message. Small mistakes make SPF fail outright rather than partly, so a record that looks fine can still break all your mail.

What this SPF checker shows

Enter a domain and the checker reads its SPF record from public DNS, then:

  • Confirms there is exactly one record. Two are a permanent error.
  • Checks every term. A typo or an unknown mechanism fails the whole record, and the term-by-term list marks the one at fault.
  • Counts DNS lookups against the limit of 10. It follows every include: and redirect= down the chain and shows what each one costs, so you can see which service is using up the budget.
  • Names the services behind the includes it recognizes, such as Google, Microsoft 365, SendGrid or Klaviyo.
  • Explains the ending. -all, ~all, ?all and +all each tell receivers something different about servers you didn’t list.

Common SPF problems

Too many lookups. Every email service you add asks for an include:, and each of those can contain more includes. Once the total passes 10, SPF fails for everything. Remove includes for services you’ve stopped using first. If that isn’t enough, move a service to a subdomain (many ESPs send from send.yourbrand.com, which has its own SPF record) or replace an include with the ip4: ranges it resolves to.

Two records. Merge them into one, keeping every include and a single ending.

An include that doesn’t exist. A typo, or a service that has changed its SPF domain. Receivers treat it as an error.

+all or ?all. The first lets any server pass; the second tells receivers nothing. Use ~all or -all.

The SPF record generator builds a corrected record from the services you use.

SPF is one of three

SPF on its own doesn’t stop anyone putting your domain in the From line. That needs DMARC, which passes when SPF or DKIM passes for your domain. Check the other two with the DKIM checker and the DMARC checker, or run all three at once with the email deliverability test.