Without MTA-STS, attackers can secretly downgrade your email connections and intercept messages in transit. Enforce TLS on every message with a cloud-managed MTA-STS policy – no manual DNS work, no infrastructure to maintain.
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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.
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.
Publish DNS CNAME records
Connect your domain to PowerDMARC with a one-time DNS update. No policy hosting required.
Sending servers validate your MTA-STS policy
Before delivery, servers check your policy to confirm TLS is required.
Only encrypted delivery is allowed
If TLS cannot be established, the message is rejected, preventing plaintext transmission.
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
One-click CNAME setup
Publish your MTA-STS DNS records 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 DNS records. 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.
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.
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.
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.
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 DNS records once and manage your policy through a dashboard. No manual hosting required.
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.
Setup takes only a few minutes. After publishing DNS CNAME records once, your MTA-STS policy is hosted and managed through the platform. From there, you can enforce TLS immediately without additional configuration.
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.
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.
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.
5-minute setup · RFC 8461 compliant · Cancel anytime
