If you choose this option, outlook will try to encrypt all outgoing e-mails. This might be a problem as encryption is done using the public RSA key of the recipient. This might not exist (insurmountable problem) or you might not have it (this can be solved by either using the PKI LDAP Server or performing a handshake with the recipient, i.e. ask them to send you a digitally signed e-mail).

If you chose "verschlüsseln" per default in the Trust Center then this is preselected. If you didn't then select it as needed.

This error message occurs when you are trying to send an encrypted message but Outlook doesn't know the recipient's public RSA key. Outlook can only "know" a public key, if you have stored the recipients data, including their user certificate as a private contact. It is not sufficient to have the recipient in your department's exchange address book etc.

One way to avoid this problem is to use the DFN-LDAP as an address book (see below).

This is an example of a received e-mail, which has been

• encrypted
• digitally signed  

The Subject is never encrypted.

The text can only be read if Outlook knows the private RSA key of the recipient. Click on the "lock" symbol.

The e-mail is encrypted and signed.
"Show Details" will depict additional information about the encryption.

Encryption details