MTA-STS Lookup Tool
Check Mail Transfer Agent Strict Transport Security records
MTA-STS (Mail Transfer Agent Strict Transport Security) enables mail service providers to declare their ability to receive TLS-secured connections and to specify whether sending SMTP servers should refuse to deliver to MX hosts that do not offer TLS with a trusted server certificate.
Domain Lookup
Enter a domain name to check its MTA-STS DNS records and policy configuration
Try examples:
Ready to Check MTA-STS Records
Enter a domain name above to check its MTA-STS DNS records and policy configuration.
What is MTA-STS?
MTA-STS (Mail Transfer Agent Strict Transport Security) is an email security standard that enables mail service providers to declare their ability to receive TLS-secured connections and to specify whether sending SMTP servers should refuse to deliver to MX hosts that do not offer TLS with a trusted server certificate.
Key Components:
- DNS TXT Record: Published at _mta-sts.domain.com to advertise MTA-STS support
- Policy File: Hosted at https://mta-sts.domain.com/.well-known/mta-sts.txt
- Mode: Can be "enforce", "testing", or "none"
- Max Age: How long the policy should be cached
How MTA-STS Works:
- Sending mail server checks for _mta-sts.domain.com TXT record
- If found, fetches the policy file from https://mta-sts.domain.com/.well-known/mta-sts.txt
- Validates that the receiving MX servers support TLS and have valid certificates
- Enforces the policy based on the specified mode
Related Tools
MX Lookup
Check mail servers
Blacklist Checker
Check IP reputation
DNS Lookup
DNS record queries
SPF Checker
Validate SPF records
DMARC Analyzer
Analyze DMARC policies
Header Analyzer
Analyze email headers
DKIM Checker
Verify DKIM signatures
WHOIS Lookup
Domain registration info
SMTP Test
Test SMTP connectivity
SSL Certificate
Check SSL certificates
DNS Propagation
Check DNS propagation
Ping Test
Test network connectivity
Traceroute
Trace network path
Subnet Calculator
Calculate IP subnets
What Is My IP
Check your IP address
Need Help?
Our tools are designed to be intuitive, but if you need assistance, we're here to help.
About Our Tools
Professional-grade email and DNS diagnostic tools trusted by IT professionals worldwide.
Free to UseNo RegistrationReal-time Results