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MTA-STS policy generator

Fill in your MX hostnames and enforcement mode. We'll output both the DNS TXT record and the policy file you need to host at mta-sts.<your-domain>/.well-known/mta-sts.txt.

For Google Workspace: *.google.com. For Microsoft 365: *.mail.protection.outlook.com. Mismatches here break mail delivery.

604800 = 7 days (recommended).

Example result for example.com

Sample data. Run the check above to see yours.

Your MTA-STS policy

Generated

Serve this file at https://mta-sts.example.com/.well-known/mta-sts.txt.

version STSv1
mode testing
mx mx1.example.com
max_age 604800

Want ongoing monitoring?

This tool is a one-shot check. PhishFence watches your domain with automated hourly monitoring (daily on Free) for DMARC changes, new lookalike registrations, and spoofing attempts.

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