Confusion Using Client Certificates in Postman for Windows

We have an API for our secure email system. One of the API calls is to simply return messages from the inbox. The call is indicated below. It includes the email address of the user account, the password for that account, and the number of messages to be returned.

  "direct_address": "",
  "password": "somepassword",
  "limit": 2

This is submitted using the POST option with a URL that requires a client certificate for Mutual TLS. Note that the client certificate for any user account had a Subject CN that matches the direct_address value (

I have both the Postman Chrome plugin and the Postman for Windows application. When I first use the Chrome plugin after starting my computer (before the certificate is cached), it prompts me for the client certificate. Once I select the correct certificate, the call works as expected. But, I can’t get this to work with the Postman for Windows application. When I try to add a certificate in Settings-->Certificates, I am prompted to enter a Host value.

Since the CN for the client certificates must match the direct_address value, I don’t really know what to use here. Also, when I use the Chrome plugin, the client certificate I use is a p12 file that includes the private key. In the Windows application, do I use a p12 file for the Key or do I just use the key file, itself?

Please let me know how to use the Windows application to do what I can successfully do with the Chrome plugin.



@empiricus for P12 certificate, you only have to set PFX file (KEY and CRT file is not required) and Passphrase if P12 certificate is encrypted.

In the Host field, enter the domain (without protocol) of the request URL for which you want to use the certificate. Know More

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