In place
The record and the policy file agree, the mode is enforce, and the policy lists every MX host.
Free MTA-STS checker
Check a domain's MTA-STS record and policy file, which tell senders to deliver its email only over TLS.
- Free, with no signup
- Saves nothing it checks
What your result means
Testing
The policy is in testing mode, so senders report failures but still deliver.
Needs fixing
The record or the policy file is missing or broken, or the policy leaves out an MX host.
Questions about the MTA-STS lookup
What is MTA-STS?
A standard that tells sending servers to deliver your email only over TLS with a valid certificate, and only to the mail servers you list.
Where does the policy file live?
At https://mta-sts.yourbrand.com/.well-known/mta-sts.txt, with a TXT record at _mta-sts.yourbrand.com that announces it.
Does a cold email domain need MTA-STS?
It protects email sent to your domain, such as replies, not the email you send. It is optional.
Found a problem? We will check the rest.
Book a deliverability audit and we will look at every domain and mailbox you send from.