S/MIME installation in Microsoft Outlook


Installing an S/MIME certificate in Microsoft Outlook offers you a secure and trustworthy method for encrypting and signing your emails. By using this certificate, you not only increase the security of your communication, but also actively protect your personal and business information from unauthorized access.


  • S/MIME certificate (can be purchased via our customer center)
  • Microsoft Outlook

Export of the S/MIME certificate as PFX file

For the installation in Microsoft Outlook we need the S/MIME certificate as a .pfx file. The certificate can be exported directly via our customer center as a .pfx file.

To do this, navigate to the certificate management and select the desired S/MIME certificate (e-mail certificate). You can export the certificate as a PFX certificate under Settings.

Then select a password for the .pfx file, this will be requested by your e-mail client later when importing.

If you have forgotten your password, you can export the certificate again in the customer center and set a new password for the .pfx file.

Installation of the S/MIME certificate under Microsoft Outlook

Once the certificate has been exported as a .pfx file, the S/MIME certificate can be stored in Microsoft Outlook by following the steps below.

To do this, navigate to the File button in the top left-hand corner of Outlook so that the overview is displayed.

Then select the Microsoft Office options.

Then use the Trust Center button and then the Settings for the Trust Center in the following window.

Open the Email Security tab and call up the certificate management via the Import/Export button.

In the following window, you can import the PFX file previously exported from the Customer Center into Microsoft Outlook by clicking on the Browse button and selecting the corresponding PFX file.

Enter the password that you assigned when exporting the certificate from the Customer Center.

Confirm the import of the S/MIME certificate with the OK button.

Finally, define the following desired settings to complete the setup of your certificate and confirm the newly selected settings by clicking on the OK button.

Your emails are now automatically digitally signed, but not automatically encrypted.

Further settings can be made afterwards via the settings in the Trust Center.

S/MIME settings

Further settings can then be made afterwards via the S/MIME settings.

Setting Description
Encrypt content and attachments for outgoing messages By default, new messages are not automatically encrypted as the recipient must have the certificate to decrypt the message.
Add digital signature to outgoing messages To ensure that new messages are automatically signed, it is necessary to activate this setting