What is TLS-RPT?
What is TLS-RPT?
TLS-RPT (SMTP TLS Reporting) is an email security standard that provides visibility into email delivery and transport security issues.
It allows organisations to receive reports about problems encountered when other mail servers attempt to send encrypted email to their domain.
While technologies such as SPF, DKIM, and DMARC focus on authenticating email senders, TLS-RPT focuses on monitoring the security and reliability of encrypted email delivery.
Why is TLS-RPT Important?
Modern email systems increasingly rely on encrypted connections to protect messages while they travel across the internet.
However, encryption issues can occur for many reasons, including:
- Misconfigured mail servers
- Expired security certificates
- DNS problems
- Third-party provider issues
- Transport security policy conflicts
Without visibility into these issues, organisations may be unaware that encrypted email delivery is failing or being degraded.
TLS-RPT helps identify these problems by providing reporting from participating email providers and mail systems.
What Does TLS-RPT Report On?
TLS-RPT reports can provide insight into situations where:
- Encrypted email delivery could not be established.
- Security policies could not be validated.
- Certificate validation failed.
- Mail servers could not meet transport security requirements.
- Email delivery was delayed or rejected due to transport security issues.
This information helps organisations understand how their email infrastructure is performing from the perspective of external senders.
Why Visibility Matters
Many email transport security problems occur silently.
Messages may still be delivered, delayed, retried, or rejected without administrators being immediately aware that an issue exists.
TLS-RPT helps organisations gain visibility into:
- Transport security failures
- Configuration issues
- Emerging problems
- Trends and recurring incidents
- The effectiveness of their email security controls
Without reporting, identifying these issues can be extremely difficult.
TLS-RPT and MTA-STS
TLS-RPT is commonly deployed alongside MTA-STS.
These technologies work together:
- MTA-STS helps define transport security requirements.
- TLS-RPT provides reporting on how those requirements are performing in the real world.
A useful way to think about them is:
- MTA-STS sets the rules.
- TLS-RPT reports on what happens when those rules are applied.
Together they help organisations improve the security and reliability of email transport.
Benefits of TLS-RPT
Organisations use TLS-RPT to:
- Gain visibility into email transport security.
- Identify delivery problems affecting encrypted email.
- Detect configuration errors.
- Monitor the effectiveness of transport security policies.
- Improve reliability and trust in email communications.
- Support a proactive approach to email security.
Why Monitoring Matters
TLS-RPT reports can contain large volumes of technical information generated by email providers around the world.
As email infrastructure evolves, new issues can emerge due to:
- Infrastructure changes
- DNS updates
- Certificate renewals
- Mail server migrations
- Third-party service modifications
Regular monitoring helps organisations identify and address problems before they impact business communications.
TLS-RPT as Part of a Security Strategy
TLS-RPT does not prevent phishing, spoofing, or email impersonation directly.
Instead, it provides valuable visibility into the health and security of email transport, helping organisations understand whether their email infrastructure is operating as expected.
When used alongside SPF, DKIM, DMARC, and MTA-STS, TLS-RPT contributes to a comprehensive email security strategy that improves trust, security, and reliability.