What is TLS-RPT (TLS Reporting)?
TLS-RPT (TLS Reporting) is a standard that provides visibility into TLS connection failures for email transmission. It works alongside MTA-STS to help you identify and fix email delivery problems, misconfigurations, and potential security issues.
While MTA-STS enforces encrypted email transmission, TLS-RPT provides the monitoring and reporting needed to ensure everything is working correctly. It's like having a security camera for your email delivery - you can see when and why TLS connections fail.
How TLS-RPT Works
When mail servers attempt TLS connections:
- Receiving servers check for TLS-RPT DNS record
- If TLS connection fails, details are logged
- Periodic reports are sent to addresses specified in the DNS record
- Reports contain JSON data showing connection failures, reasons, and statistics
TLS-RPT reports help you identify problems like expired certificates, misconfigured mail servers, or potential attacks before they cause email delivery failures.
Why TLS-RPT is Critical for Your Business
1. Visibility into Email Delivery Problems
Without TLS-RPT, you have no way to know:
- When TLS connections are failing
- Why emails aren't being delivered
- Which mail servers are having problems
- If certificates are expiring or invalid
- If there are configuration issues
TLS-RPT provides this visibility through detailed reports, helping you proactively identify and fix issues before they impact email delivery.
2. Security Issue Detection
TLS-RPT reports can reveal:
- Certificate expiration warnings
- Invalid certificate configurations
- Potential man-in-the-middle attacks
- Misconfigured mail servers
- Security policy violations
3. MTA-STS Monitoring
TLS-RPT is essential when using MTA-STS in "testing" mode. The reports show:
- How many TLS connections are succeeding
- How many are failing and why
- Whether it's safe to switch to "enforce" mode
- What needs to be fixed before enforcement
4. Proactive Problem Resolution
TLS-RPT enables proactive problem resolution by:
- Alerting you to problems before they cause delivery failures
- Providing detailed information to diagnose issues
- Helping you fix configurations before they impact customers
- Monitoring the health of your email infrastructure
What Can Go Wrong Without TLS-RPT?
No Visibility into Problems
Without TLS-RPT, you're blind to:
- TLS connection failures
- Certificate expiration issues
- Configuration problems
- Potential security attacks
- Email delivery issues
Reactive Problem Solving
Without TLS-RPT, you only discover problems when:
- Customers complain about missing emails
- Email delivery completely fails
- Certificates expire and break everything
- Security incidents occur
By then, it's too late - damage is already done.
Inability to Safely Deploy MTA-STS
Without TLS-RPT, you cannot safely deploy MTA-STS because:
- You don't know if TLS connections are working
- You can't identify problems before enforcement
- You risk breaking email delivery when switching to enforce mode
- You have no way to monitor MTA-STS effectiveness
How TLS-RPT Works: Technical Deep Dive
TLS-RPT DNS Record
TLS-RPT uses a DNS TXT record at _smtp._tls.domain.com containing:
- v=TLSRPTv1: Version identifier (must be TLSRPTv1)
- rua= Reporting URI(s) where reports should be sent (mailto: or https://)
_smtp._tls.prismweb.com. TXT "v=TLSRPTv1; rua=mailto:tls-reports@prismweb.com"
TLS-RPT Reports
Reports are sent in JSON format and contain:
- Organization Name: Domain that sent the report
- Date Range: Time period covered by the report
- Contact Info: Contact information for the reporting organization
- Policies: List of MTA-STS policies evaluated
- Connection Results: Statistics on successful and failed TLS connections
- Failure Reasons: Detailed reasons for TLS connection failures
Report Delivery
Reports can be delivered via:
- mailto: Email address (reports sent as email attachments)
- https: URL endpoint (reports sent via HTTPS POST)
Multiple reporting URIs can be specified, separated by commas. Reports are typically sent daily, but frequency depends on the reporting organization's configuration.
Failure Reasons
TLS-RPT reports categorize failure reasons:
- starttls-not-supported: Server doesn't support STARTTLS
- certificate-expired: Certificate has expired
- certificate-invalid: Certificate is invalid or self-signed
- tlsa-invalid: DANE TLSA record is invalid
- sts-policy-invalid: MTA-STS policy is invalid
- sts-webpki-invalid: MTA-STS policy file certificate is invalid
TLS-RPT Best Practices
1. Always Configure TLS-RPT with MTA-STS
TLS-RPT is essential when using MTA-STS. It provides the visibility needed to safely deploy and monitor MTA-STS policies.
2. Use Dedicated Email Address or Service
Use a dedicated email address (e.g., tls-reports@prismweb.com) or a TLS-RPT analysis service to receive and process reports. This keeps reports organized and makes analysis easier.
3. Regularly Review Reports
Review TLS-RPT reports regularly to:
- Identify and fix configuration issues
- Monitor certificate expiration
- Detect potential security problems
- Ensure MTA-STS is working correctly
4. Use Report Analysis Tools
Consider using TLS-RPT report analysis services that parse JSON reports and provide visual dashboards, making it easier to identify trends and issues.
How PrismWeb Ensures Complete TLS-RPT Protection
At PrismWeb, we perform comprehensive TLS-RPT validation:
- DNS Record Verification: We check that the _smtp._tls DNS TXT record exists and is properly formatted
- Reporting URI Validation: We verify rua= addresses are properly configured
- MTA-STS Integration: We ensure TLS-RPT is configured alongside MTA-STS
- Report Processing: We help you set up report analysis and monitoring
When you host with PrismWeb, TLS-RPT is properly configured, reports are monitored, and issues are proactively identified and resolved. We ensure you have complete visibility into your email delivery security. This is one of our 16 comprehensive security checks that most providers skip entirely.