Question 1

What is an SPF record?

Accepted Answer

SPF (Sender Policy Framework) is a DNS TXT record that lists which mail servers are authorized to send email for your domain. Receiving servers check SPF to detect spoofing.

Question 2

What is the SPF 10-lookup limit?

Accepted Answer

RFC 7208 limits SPF evaluation to 10 DNS lookups (include, a, mx, redirect, exists mechanisms). Exceeding this causes a permerror and SPF fails. ip4 and ip6 mechanisms do not count toward this limit.

Question 3

Should I use ~all or -all?

Accepted Answer

Use ~all (softfail) while setting up — it flags unauthorized senders without blocking them. Once you're confident in your SPF record, switch to -all (hardfail) to tell receivers to reject unauthorized mail.

SPF Record Builder