Secure Email

CheckTLS Directly From Outlook

Check that every copy of every email you send will be encrypted. Simply and automatically.

Meet your HIPAA, GDPR, PCI-DSS, or other email transport requirements using only Outlook. No extra steps, equipment, or changes to your network.

The CheckTLS Outlook Add-in makes the power of the CheckTLS website available to everyone. No technical knowledge required.

Don't worry — the complete website with all it's capabilities is still here and available as always, starting below.

Internet email

The Red Arrow

Email has three parts: your end, their end, and the Internet in the middle. You control your end, they control their end, but that middle part is "uncontrolled".

CheckTLS is about the red parts of the picture. We help you secure and test the parts of your email system that touch the Internet. Many places ignore these areas because it's too hard or they don't know how to get started.

And no matter how sophisticated your Internet touching systems are, they should be verified and regularly tested.

The government (NIST) just just released Special Publication 800-177 (Revision 1) entitled Trustworthy Email (nice overview at Nextgov) that shows how CheckTLS can help.

No matter your security level, this site will help.

Internet Email Security May Be Easier Than You Think

Most email systems can encrypt email in compliance with US NIST, HIPAA, GDPR, HITECH, PCI DSS, Sarbanes-Oxley, GLBA, SB1386, SEC 17a-4, NASD3010, FRCP, FINRA, etc.

(You may need to whitelist we do not keep or use your address, see our privacy policy)

If your Confidence Factor℠ was 90 or better, your email has the necessary strong encryption required by these security standards. We can make sure you are using it correctly: see How To Use CheckTLS.

If your Confidence Factor℠ was less than 90, you're in the right place. We can help you get there. See Solve Secure Email Problems for more information.

Email Security Compliance May Be Easy Too

As long as your existing email uses strong enough encryption to communicate Protected Information over the Internet, it meets your security compliance requirements. So once you know your email can do the required strong encryption, you just have to make sure it does.

Verified TLS℠

Verified TLS℠ makes sure your email uses and continues to use encryption. Verified TLS℠ makes your existing email security compliant.

Required or Not, Secure Email is Important

Even if your organization is not required to comply with one of the listed rules and regulations, you certainly communicate information you do not want just anyone to see. Use Verified TLS℠ to make sure your email is protected.

Yes, There is More

The test above scores how well your email system receives email. How well does it send email? How about where you send sensitive information: your customers and vendors. How well do they receive your emails?

See Secure Email Compliance for more information.

And, back to the Red Arrow, we realize that your part, your green arrow above, has data encryption at rest, data retention, data protection, data destruction, and other ramifications. We just make Secure Email Internet Transport easy. We are the Red Arrow.

TLS 1.3

CheckTLS email works with TLS 1.3, as do most of our tests.

Test TLS 1.3 on our email to see how it works. Compare the results with tests on your site.

The IETF released TLS 1.3 in August, 2018. This new release is a big deal (see this overview at Kinsta).

Transport Layer Security (TLS) is the most important piece of email transport security, so this new version is very important to us and to our clients. We cover email broadly and deeply, so this new version affects much of our tests and tools. We are continuing to add TLS 1.3 probes, discovery, and reporting to our site. We welcome feedback, suggestions, and reports for what parts of our site could benefit from adding or enhancing TLS 1.3 support. Contact Us

Outlook TLS Add-In

Outlook can automatically check each address on an email when you click Send. If everything is secure, Outlook sends the message, otherwise Outlook asks you what to do.

This give you immediate, at-the-source email security. Working with all of the addresses at once has many advantages, and meets your security compliance requirements in a straight forward manner.

More information can be found at Check For TLS From Inside Outlook.

How To Use CheckTLS

CheckTLS tests email systems:

  • superficial to thorough
  • one time to continuous
  • minimal to complete
  • overview to precise detail

Our site is free for non-commercial use. Commercial users have access to more features, faster results, stored tests, and automatic testing.

We Suggest You Approach CheckTLS in This Order:
(click below to expand each item) Check How You Get Messages from a Good Email System   (more...) (run) Check How You Put Messages into a Good Email System   (more...) (run) Show Protocols, Ciphers, and Vulnerabilities of an Email System   (more...) (run) Check Your Email End-To-End, Both Send and Receive at Once   (more...) (run) Check Many Emails at Once   (more...) (run) Check If You Force Someone Else to Encrypt Messages to You   (more...) (run) Check If You Force Message Encryption to Someone Else   (more...) (run) Test a Protected (Private) Email System   (more...) (run) Store Tests on CheckTLS   (more...) (run) Monitor an Email Address or Email System   (more...) (run) Meet Email Compliance Using Only CheckTLS   (more...) Put CheckTLS to Work for You   (more...) Put CheckTLS on your WebSite or Intranet   (more...) (run) Work with Certificates Sniff Packets on the Internet   (more...) (run) Test Any Internet Service   (more...) (run)

OutSource Email Support to Us

We create a custom CheckTLS site that implements your security requirements. Your trading partners then work with us to meet your requirements.

We show them why their email does not meet your requirements, and we let them see the changes they make on their systems in real-time. All without bothering you.

Once they meet your requirements on the custom site, they and you know their email will work with your email and meet your email requirements.

Once you approve a trading partner, we will monitor that they stay compliant with your requirements. And we send error alerts to both them and you, so they and you know about problems sooner.

As your email security requirements change in the future, you can use the monitoring database on our system to do "what if" analysis over your list of trading partners. By adding the new security requirements to your custom site on CheckTLS before you implement them in production, you can give the trading partners the time and tools they need to meet your new requirements. And you can send specific instructions to the ones that need to take action based on your "what if" analysis.

Contact Us for more information about a custom CheckTLS site (e.g.

CheckTLS Offers

Commercial Services are a very low cost solution for HIPAA/GDPR compliance or other security mandates. No devices, no on-line services — just add verification and audit to your existing email systems!

Email Tools are quick and easy tools to test email and email security, specifically TLS encryption.

Cloud Tools are network "wire" tools that we have invented to work "in the cloud". Capture packets or analyze protocols out on the Internet.

Web Service API lets you use CheckTLS in your own data processing.

Embed API lets you put CheckTLS on your own intranet or public web site.

Much of our site is free for casual, non-commercial use.

Commercial Services


We are part of the security policies and operations of some very large and prestigious financial institutions, health care systems, insurance companies, and law firms. Why? Two reasons: our tests work and we save them money!

Secure Your Company Email

You can use CheckTLS instead of expensive email appliances or on-line email services to meet internal security requirements, contractual security requirements, and government security requirements. One less moving part in your email chain and one less expense. Our tests are a very inexpensive answer to PHI (HIPAA/HITEST), GDPR, PCI-DSS, PII, US NIST requirements.

If you already have extra in-line or on-line email security, CheckTLS can verify they're working and monitor them to be sure they keep working. A few extra bucks a month to make sure all that sophisticated stuff is working.

Protect Your Company from Your Business Partners

Use CheckTLS to make sure your trading partners are secure enough to do business with you. As part of your new vendor and new customer process, verify that their email scores a Confidence Factor℠ of 90 or above on our //email/testTo: ("TestReceiver") test.

Broadly Applicable

Whether you are a small shop that needs something simple and low cost, a medium business that needs to beef up security to meet increasing scrutiny by your trading partners, or an enterprise organization that wants some oversight of many security facets, CheckTLS can solve many of your security challenges faster, easier, and at significantly less cost.


Our tests are non-invasive, non-intrusive, and non-obtrusive. They require no changes to your or any other system. They cause no extra processing and should not trip any security alarms.


Our tests are simple, open, and proven. For six years we have been doing over a million tests a year. We research all questionable results, and we welcome feedback and suggestions. You can turn up the detail and audit everything we do.

Business Benefits
  • Email security at low cost, easy install, no risk
  • Safeguard "Protected" information: PHI, PCI, PII, etc.
  • Monitor your email from the Internet
  • Add regular, independent verification to your Security Policy
  • No changes to your email: no devices or routing
  • Good first step into email security
  • Good next step no matter how advanced your security devices and services
  • Demonstrates effort and consideration of security
  • We can help with your security designs and documentation
Business Users Have Priority
  • Run tests faster and at a higher priority
  • Program multiple tests, save them, and run them on a schedule
  • Monitor CheckTLS and your email (fail-safe monitoring)
  • Add custom test and/or monitor icons on your desktop or your phone
  • Use the CheckTLS API to automate testing and interface with your IT
  • Receive unlimited support
  • Meet requirements for Protected Information (PHI, PCI, PII, NIST, etc.)
  • Assistance and sample language for HIPAA/GDPR and other compliance

Sleep better knowing someone else is watching over your email.

Email and Cloud Tools