For systems that are specially configured to Mandate TLS, this is a very important test, especially since it can test custom/private email systems (see FULL Version below)

How to run it

Type in an email address that has Mandatory TLS turned on.

Leave the Output Level set to "Detail".

Click the Run Test button.

Use the address to see a successful test.

What it does

When you click Run Test, TestMandatoryReceiver makes sure that Mandatory TLS is working. It does not accept the receiver's invitation to use TLS but instead tries to send an email as plain text.

TestMandatoryReceiver performs some of the steps that Internet email systems go through to send email. When the remote system offers encryption options, TestMandatoryReceiver ignores the offer and tries to send the email in plain text. Allowing plain text email is the desired behavior of most Internet email systems, so most Internet email systems should fail this test. As with TestReceiver, it records every command and byte of data it sends and every answer and byte of data that it receives, and it also never actually sends an email

What it shows

Assuredness Factor

For all Output Levels, the first thing TestMandatoryReceiver shows is an Assuredness Factor. This is either zero or 100, showing whether or not Mandatory TLS is working. For domains with multiple email servers (MX hosts), it checks each one. Every MX host must Mandate TLS or the overall score is zero.

MX Matrix

The next level of output is the MX Matrix. TestMandatoryReceiver groups the steps of testing Mandatory TLS into 5 stages. The MX Matrix shows, for each MX host, how long each stage took and whether it was successful or not. Use the MX Matrix to look by MX Host where a weaknesses is in the system.

See the TestReceiver Full Documentation for more information about the MX Matrix stages.


The next levels of output is Detail. Detail is the log of TestMandatoryReceiver's interaction with the recipient's email system. Because TestMandatoryReceiver finds out very quickly if the recipient's email will allow plain text email, there is not much additional output in the Detail level and it is self-explanatory.

FULL Version

TestMandatoryReceiver has the same FULL Version options as normal TestReceiver so you can test custom/private email systems for Mandatory TLS. See email/test/To: for more information.

Input Fields
TestReceiverAssureTLS parameter entry
  1. - + (less/more output)
FULL Version

See what else you can test: How To.

Test Results

Test results will show here when a test is run.