Free SPF Record Flattening Tool

What is SPF?

SPF (Sender Policy Framework) is a DNS record that tells receiving mail servers which servers are allowed to send email for your domain. It helps protect against spoofing and phishing.

Why flatten an SPF record?

An SPF record can only have up to 10 DNS lookups. If your record includes lots of third-party services (Microsoft 365, Google, mail gateways, etc.), you can easily hit this limit. Flattening replaces those include: lookups with direct IP addresses, keeping you under the limit.

Why use sub-SPF records?

DNS also limits TXT record length to 255 characters. If a flattened record is too long, it's automatically split into _spf1, _spf2, and so on. Your main SPF then just includes those sub-records, making the whole setup valid and easier to manage.