Free Tool
SPF Record Builder
Build valid SPF records while tracking the 10-lookup limit. Select your email providers and we'll generate the correct syntax.
What counts as a lookup?
include:, a, mx, ptr, and exists mechanisms all require DNS lookups. ip4: and ip6: do not.Why the 10-lookup limit?
RFC 7208 limits SPF to 10 DNS lookups to prevent denial of service attacks. Exceeding this causes a PermError, which fails DMARC alignment.
What is SPF flattening?
SPF flattening resolves includes to their IP addresses, eliminating lookups. But IPs can change, requiring regular updates or a service like Valimail.
Check your full email setup
Use our Email Deliverability Checker to verify SPF, DKIM, DMARC, and more.
Calculate your AWS SES costs
See exactly what you'll pay for email sending plus the full infrastructure — EventBridge, Lambda, SQS, and DynamoDB.
Want to learn more about SPF and the 10-lookup problem?
Read: The SPF 10-Lookup Limit Explained