Installing and Using your Secure Email Certificate with Thunderbird

Assigning your Certificate to your email account:

These instructions assume you have previously followed the instructions to save your certificate to a secure location.  Thunderbird has it's own certificate store and does not automatically pick up certificates from the Windows certificate store.

  • Open Thunderbird
  • Select Tools from menu
  • Select Options from drop down menu
  • In dialog box that appears select Advanced tab
Thunderbird Advanced Options

Click on the Manage Certificates...


Manage Certificates – Thunderbird

Browse to the location of your PKCS12 certificate and enter any necessary passwords. Once complete the certificate will appear and you will be able to digitally sign e-mails you send out.


Signing an single Email:

Signing an email ensures the recipient knows the email has come from you and informs him / her if it has been tampered with since being signed.

  • Compose your email and attach files as usual
Thunderbird Digital Sign Message

Encrypting a single Email:

Encrypting an email ensures that only the recipient may view the email content and any attachments. Note: in order to encrypt an email for the recipient you must have the recipient's digital certificate, and their digital certificate must be assigned to the relevant entry in your address book

  • Compose your email and attach files as usual
  • Ensure the recipient has a Digital Certificate and you have assigned the Certificate to their entry in your contacts area
  • Follow the process above and choose Encrypt This Message
  • Click Send button

Signing and Encrypting as default.

  • Open Thunderbird
  • Select Tools from menu
  • Select Account Settings from drop down menu
  • In dialog box that appears select Security tab
  • Select the appropriate certificates you wish to Sign and/or Encrypt your mails.  Note that the same certificate does not have to be used for both options.
Account Settings – Thunderbird