Hosted MTA-STS
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Your Emails are Vulnerable Without MTA-STS
Most email servers rely on opportunistic TLS, which means encryption is preferred, but not enforced.
Attackers can exploit this gap to downgrade connections to plaintext, intercept messages, or tamper with communications in transit. Misconfigured domains are especially vulnerable to persistent monitoring and data exposure.
Without an enforced MTA-STS policy, your email traffic can be exposed without you ever knowing.
What is MTA-STS?
MTA-STS (Mail Transfer Agent Strict Transport Security) is a standard (RFC 8461) that allows domain owners to enforce TLS encryption for email delivery.
Instead of relying on opportunistic TLS, you publish an MTA-STS policy that instructs sending servers to only deliver messages over secure connections, or not at all. This prevents downgrade attacks and ensures messages are never transmitted in plaintext.
Hosted MTA-STS makes this enforcement simple by managing your policy, certificates, and updates in the cloud.
How Hosted MTA-STS Works
1
Publish a single CNAME record
Connect your domain to PowerDMARC with a one-time DNS update. No policy hosting required.
2
Sending servers validate your MTA-STS policy
Before delivery, servers check your policy to confirm TLS is required.
3
Only encrypted delivery is allowed
If TLS cannot be established, the message is rejected, preventing plaintext transmission.
Why Choose PowerDMARC for MTA-STS
One-click DNS setup via CNAME
with no ongoing maintenance required
Fully RFC 8461 compliant
with modern TLS support out of the box
Built-in TLS-RPT reporting
for absolute delivery visibility and debugging
No infrastructure dependencies
or certificate management required, everything handled for you
Complete authentication stack
including DMARC, SPF, DKIM, MTA-STS, TLS-RPT, and BIMI
Everything Managed On Your Behalf
One-click CNAME setup
Publish your MTA-STS DNS record in minutes. No manual configuration or file hosting required.
Zero infrastructure to manage
We host your MTA-STS policy file and TLS certificates. No servers or renewals to maintain.
Minimal deployment on your side
Your team only needs to publish a DNS record. We handle everything else.
Update policies without touching DNS
Switch between testing, enforce, and none modes instantly from the dashboard.
RFC 8461 compliant, latest TLS standards
Fully compliant with MTA-STS specifications and modern encryption requirements.
Monitor TLS delivery with TLS-RPT
See which sending servers failed TLS delivery and why with built-in TLS-RPT reporting included.
See Every TLS Delivery Attempt with TLS-RPT
MTA-STS enforces encryption, but TLS-RPT shows you what’s actually happening.
PowerDMARC’s TLS-RPT reporting gives you visibility into failed TLS connections, misconfigured senders, and delivery issues in plain English so you can fix problems before they impact your email flow.
Trusted by Security Teams Worldwide
Protecting thousands of domains globally across enterprises, MSPs, and government organizations.
The most notable feature of PowerDMARC is the complete visibility it provides over email authentication. The platform not only covers SPF, DKIM, and DMARC, but also integrates other key protocols such as MTA-STS, TLS-RPT, and BIMI, enabling a comprehensive approach to email security in one place.
Frequently Asked Questions
What is MTA-STS, and how is it different from STARTTLS?
STARTTLS enables encryption if both servers support it, but it does not enforce it. MTA-STS builds on this by requiring TLS for delivery. If encryption cannot be established, the message is not delivered. This prevents downgrade attacks and ensures secure email transmission.
What is an MTA-STS policy, and how do I publish one?
An MTA-STS policy is a file that defines how your domain enforces TLS for incoming email. It specifies allowed mail servers and required encryption settings. With Hosted MTA-STS, you publish a single DNS record and manage your policy through a dashboard. No manual hosting required.
What is a downgrade attack, and how does MTA-STS prevent it?
A downgrade attack occurs when an attacker forces an email connection to fall back from encrypted TLS to plaintext. MTA-STS prevents this by enforcing TLS delivery. If encryption fails, the message is rejected instead of being sent insecurely.
How long does it take to set up Hosted MTA-STS with PowerDMARC?
Setup takes only a few minutes. After publishing a DNS CNAME record, your MTA-STS policy is hosted and managed through the platform. From there, you can enforce TLS immediately without additional configuration.
Does MTA-STS work with Google Workspace and Microsoft 365?
Yes, MTA-STS is compatible with major email providers, including Google Workspace and Microsoft 365. It ensures secure email delivery between servers regardless of your email hosting platform.
What is TLS-RPT, and does it come with Hosted MTA-STS?
TLS-RPT (SMTP TLS Reporting) provides visibility into TLS delivery attempts and failures. PowerDMARC includes TLS-RPT reporting alongside Hosted MTA-STS, allowing you to monitor encryption issues and troubleshoot delivery problems.
Does MTA-STS work alongside DMARC and SPF?
Yes, MTA-STS complements DMARC and SPF. While DMARC and SPF protect your domain from spoofing, MTA-STS secures the transmission of emails between servers. Together, they form a complete email authentication and security framework.
Secure Your Email in Transit Today
5-minute setup · RFC 8461 compliant · Cancel anytime
