Self-signed certificates in Mozilla Thunderbird

How to set a self-signed certificate in Mozilla Thunderbird as trustworthy

If you use self-signed certificates in Kerio Connect, users with Mozilla Thunderbird may experience problems with secure authentication from a directory service (LDAPs protocol).

If this is your case, create an exceptions for your self-signed certificate in the application.

  1. In Mozilla Thunderbird, go to Tools > Options > Advanced > tab Certificates.
  2. Click on View Certificates and go to tab Servers.
  3. Click on Add Exception.
  4. Enter the name of your mail server and click on Get Certificate.


Do not forget to use the port number of the mail server.


  1. Save the exception.


We recommend to check the option for permanent storage of the exception.

Your self-signed certificate is now considered as trustworthy by Mozilla Thunderbird.

Server certificate is not available

If your Thunderbird has a problem acquiring the server certificate, follow these steps:

  1. In Mozilla Thunderbird, go to Tools > Options > Composition > tab Addressing.
  2. Check the Directory Server option and click on Edit Directories > Add.
  3. Enter the necessary information a check Use secure connection (SSLSecure Sockets Layer - A protocol that ensures integral and secure communication between networks.). Confirm the dialog.
  4. In the list of directory service servers, select the one you have just created a open it.
  5. On tab Offline, click on Download Now.
  6. Save the settings.
  7. Now you can add the exception as mentioned above.