Import a personal certificate into Outlook and Outlook Express

Need to use a certificate on the local machine to sign or encrypt emails in Outlook or Outlook Express

After you have your certificate installed on Windows, please follow the document link below for your version of Outlook or Outlook Express.

Outlook 2010/2013/2016

1. Open Outlook and click the File tab in the ribbon.
2. On the left hand menu list, click Options > Trust Center > Trust Center Settings… button.
3. A window named Trust Center will appear. Click E-mail Security (on the left). You should see a drop down field next to Default Setting. Click Settings next to this field.  
4. In Change Security Settings window, two options to Choose will be presented under Certificates and Algorithms. One under the Signing Certificate and another under the Encryption Certificate section.
5. In the Certificates and Algorithms section of the Change Security Settings window, you should see the heading Signing Certificate. Click Choose.  A new window will appear, named Select Certificate. In this window, you will choose the Digital Certificate you would like to sign with, from a list of certificates installed on this computer.
6. Also in this window, you will choose the Digital Certificate. Outlook will choose the strongest encryption algorithm possible according to the encryption certificate.  Once done, click Ok.

Outlook 2007

1. From the Outlook menu bar select the Tools > Options > Security > Import/Export
2. Select Import existing Digital ID from a file
3. Click Browse.
4. Navigate to the exported certificate, select the certificate and click Open
5. Type the password you created when you exported the certificate and enter the Digital ID name in the text boxes assigned
6. Click OK

Outlook Express 5.x/6.x

1. Click Tools > Accounts.
2. Click on the Mail tab then click Properties.
3. Under General, you should see your name and email address. Click on the Security tab.
4. You will see a box called Certificate. If empty, click Select.
5. Choose your certificate by highlighting it and then click OK. The hash algorithm should state SHA-1.
6. Repeat the same procedure for Encryption Preferences.  You can choose a different Encryption Algorithm other than the default to fit your needs.
7. Click OK.

Outlook Express 4.x

1. Click Tools > Accounts.
2. Click the Mail tab then click the mail account in which you want to use a Digital ID.
3. Click Properties.
4. On the Security tab, click the Use a digital ID when sending secure messages from <e-mail address> check box to select it, and then click Digital ID.
5. Click the appropriate Digital ID
6. Click OK twice, and then click Close.