Table of Content

1. Installing the S/MIME Certificate
1-1. Operating Environment
1-2. Prerequisites
1-3. Install Procedure
2. Sending Digitally Signed E-mails
2-1. Sending Digitally Signed E-mails
2-2. How to Confirm a Sent E-mail That Was Digitally Signed

1. Installing the S/MIME Certificate

1-1. Operating Environment

The procedures only in the following environment are described in this document:

1-2. Prerequisites

The prerequisites for using the S/MIME Certificate in Mozilla Thunderbird are described.
Replace the technical terms according to the user environment in which the S/MIME Certificate will be used.
(The procedures required for Mozilla Thunderbird 52.0 are described in this document.)

1-3. Install Procedure

Installing the Certificate

1. Open Mozilla Thunderbird, right click on the [mailuser] (account name) and select [Settings (E)].
   
   
   
2. The [Account Settings] screen will appear. Select [Security] in the account profile, listed on the left. Click [Manage Certificates...(M)].
   
   
   
3. In the [Certificate Manager] pane, select [Your Certificates] tab and click [Import... (M)].
   
   
   
4. As you can browse the certificate file(s) to import, select the certificate to import and click [Open (O)].
   
   
   
5. The [Password Entry Dialog] box will pop up. Enter the password for encrypting this certificate backup in the [Password:] box, and click [OK].  
   
   
   
6. Click [OK] in the [Alert] dialog box.  
   
   
   
7. In the [Certificate Manager] pane, make sure that the certificate is now installed, and click [OK].
   
   
   
8. The [Account Settings] screen will appear. Select [Security] in the account profile, listed on the left. Click [Select...(S)].
   
   
   
9. In the [Select Certificate] dialog box, select the S/MIME Certificate from the [Certificate] drop down list, and click [OK].
   
   
   
10. Click [No (N)].
    
    
    
11. Check the [Digitally sign messages (by default) (D)] checkbox, and click [OK].
    
    
    This completes the S/MIME Certificate installation.

2. Sending Digitally Signed E-mails

2-1. Sending Digitally Signed E-mails

How to Send Digitally Signed E-mails

1. Open Mozilla Thunderbird, and click the [Write] button.
   
   
   
2. In the [Write: Foobar] screen, click the downward arrow on the right side of the [Security] button and select [Digitally Sign This Message (M)] from the drop down list.
   
   
   
3. Write the message. 
   When finished, click [Send].
   
   
   This completes sending digitally signed e-mails.

2-2. How to Confirm a Sent E-mail That Was Digitally Signed

How to Confirm a Sent E-mail That Was Digitally Signed

1. Select a sent e-mail that was digitally signed from the [Sent] folder.
   
   
   
2. Click the [Envelope] icon.  
   
   
   
3. In the [Message Security] dialog box, click [View Signature Certificate].
   
   
   
4. The [Certificate Viewer] will appear. Select the [General (G)] tab and make sure that the tab shows "This certificate has been verified for the following uses:" on its top.
   
   
   This completes confirmation of a sent e-mail that was digitally signed.