Suped

Knowledge base
/
Email authentication

MTA-STS

A comprehensive collection of questions and answers about MTA-STS email authentication from email marketers, experts and technical documentation.
Does MTA-STS validate the MX records of a domain?
What is the recommended 'max_age' for an MTA-STS policy?
Does MTA-STS require a dedicated server for its policy file?
What is the content-type for an MTA-STS policy file?
What is the format of the MTA-STS policy file?
What is the purpose of the MTA-STS 'mx' rule?
What is the default port for the MTA-STS policy lookup?
What happens if an MTA-STS policy file is not found?
What is the minimum recommended 'max_age' for an MTA-STS policy?
Does MTA-STS secure the entire email path?
PreviousNext
DMARC monitoring

Start monitoring your DMARC reports today

Suped DMARC platform dashboard

What you'll get with Suped

Real-time DMARC report monitoring and analysis
Automated alerts for authentication failures
Clear recommendations to improve email deliverability
Protection against phishing and domain spoofing
Get started - free
Product
DMARC monitoring
SPF flattening
Blocklist monitoring
MSP
Pricing
Tools
DMARC record generator
Blocklist checker
Email tester
Resources
API docs
Customers
Blog
Guides
Knowledge base
Company
About
Trust and security

Suped

Privacy policy
Terms of service
© 2026 Suped Pty Ltd
LinkedInX