In Outlook, go to the File tab, go to Options and select in the Security Centre the Settings for the Security Centre in the Security Centre:

In the Email security sub-item, you can first make the setting „Add digital signature to outgoing messages“. This setting is recommended so that e-mail messages are signed by default. Also activate „Send signed messages as plain text“.

Then click on import.

In the window that opens, enter the path to your backup copy of the certificate, the password you used to protect your backup copy and your name. Click ok.

In the following dialogue, please select the „Security level“ option

The „Medium“ option is selected by default.

We recommend the „High“ option. This means that a protection password is requested when accessing the private key of the certificate, which is required for the signature. You must specify this in the next dialogue.

In the application, the private key is stored in Outlook until the next start, so you do not have to re-enter it for every email.

After importing the certificate, it makes sense to replace the display name in the certificate with a display name in the certificate.

To do this, hold down the Windows key on the keyboard and simultaneously press R. Enter certmgr.msc in the Open: field.

Click on OK.

The certificate manager opens. In the left-hand column, switch to the folder Own certificates → Certificates.

Localise the certificate you have just imported (e.g. use the column expiry date).

Enter the following in the field Display name: field, enter a unique name for the certificate, e.g. Group mailbox xyz@haw-landshut.de.

Click on OK to save the change and close the certificate manager.

Back to Outlook → Trust Centre.

Click on Settings…(1)then click on New(2)and assign a meaningful name, e.g. Mailbox xyz

Click on Select…a selection of the imported certificates appears.

Click on Further options.

Select the certificate with the group mailbox xyz@haw-landshut.de and click OK to close the window.

In the window Change security settings window, under Hashalgoritumus select SHA256 under Hashalgoritumus.

You can now sign and encrypt messages. When creating a new message, you will find the options for encrypting and signing under „Options“. Signing should be set by default, so you don't need to do anything else.

You can only encrypt if you have previously entered the public key of the recipient beforehand. This works, for example, if the recipient has previously sent you a message signed by them. This usually contains their public key and you can reply to them in encrypted form.

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Deutsche Version: SMIME in Outlook