SPF Record Builder
List the IP ranges and includes that send your mail, and this assembles a valid SPF record — normalising the ranges, removing duplicates and counting the DNS lookups against the limit of ten.
About
Writing an SPF record by hand is mostly bookkeeping: normalising ranges, avoiding duplicates, keeping under the lookup limit and ending with the right default. This builder takes a plain list of IP ranges and includes and assembles the record for you, showing the lookup count and length before you publish it.
How to use
- List the addresses and includes that send your mail, one per line.
- Choose the default for everything else, usually -all.
- Build the record, then publish it as a single TXT record on the domain and verify it with the SPF checker.
Frequently asked questions
Can I include a whole subnet?
Yes. Write it as a CIDR block such as 198.51.100.0/24. The builder clears any host bits so the network address is correct and tells you when it has done so.
What happens if I go over ten lookups?
The record stops working for receivers that enforce the limit, which is most of them. The builder counts includes against the limit and warns you before you publish.
Why does the record length matter?
DNS stores text in chunks of at most 255 bytes. A longer record is still valid, but it depends on your provider splitting and recombining the strings correctly, so it is worth checking afterwards.