Question 1

What is the SPF 10 DNS lookup limit?

Accepted Answer

RFC 7208 limits SPF records to 10 DNS lookups during evaluation. Each include:, a, mx, redirect=, exists, and ptr mechanism costs one lookup. If your record exceeds 10 lookups, mechanisms after the limit are silently ignored, meaning some authorized senders may fail SPF checks.

Question 2

How do I flatten my SPF record?

Accepted Answer

Flattening replaces include: mechanisms with their resolved ip4: and ip6: entries. This reduces DNS lookups to zero since IP mechanisms don't require lookups. However, flattened records are static — if your email providers change their IPs, you need to re-flatten.

Question 3

Is this SPF flattener free?

Accepted Answer

Yes, completely free. We resolve your SPF record using public DNS queries and show you the full include tree, lookup count, and flattened result.

SPF Flattener