Email & DNS

SPF Record Generator

Build an SPF TXT value from the senders you explicitly authorise.

Calculations run in your browser. The tool does not send your inputs to a server.

01Your inputs

Local workspace

Start with the sample below, or enter your own values.

Domain

Authorised IPv4 addresses or CIDRsThe sample is editable. Keep the input format consistent with the action you choose.

Authorised IPv6 addresses or CIDRsThe sample is editable. Keep the input format consistent with the action you choose.

Include domains, one per linePut each entry on its own line, following the example format.

Authorise domain A / AAAA addresses

Authorise domain MX addresses

Unmatched sender policy

02Your result

Your result will appear here. Choose an action after checking your inputs.

A quick guide

How to use this tool

Check the example and the unit beside each input.
Enter your values and choose Build.
Review the result and assumptions, then copy what you need.

Reset example restores the starting values. Clear removes text and number inputs, returns choices to their first valid option, and removes the result.

Reference guide

Explanation and worked examples

Enter IP addresses or CIDRs and provider include domains. A and MX authorisation are optional. The record ends with your chosen unmatched-sender policy. Nested DNS lookups, existing records and real mail delivery must be checked separately.

Use in day-to-day IT work

Prepare one SPF record before onboarding or changing an outbound email provider.

Checks before applying the result

Inventory application servers, third-party senders and forwarding arrangements. Use only include domains supplied by your provider.
Keep one SPF record at the owner. Evaluate include chains and the ten DNS-querying-term limit against live DNS before publishing; an offline syntax check cannot establish delivery success.

New to the terminology?

SPF: Sender Policy Framework: authorises sending hosts for a domain used by SMTP.
MTA-STS: A published policy for authenticated TLS delivery to declared MX hosts.
TTL: How long a DNS answer may normally remain cached.

Keep exploring

How calculations work and where the models stop →