Configure Outlook to encrypt outgoing e-mails (optional)
You can configure Outlook to send digitally signed and/or encrypted e-mails.
|These instructions were created using Outlook 2016 on Windows 10 (Latest update 23.04.2020).|
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.
This is an example of a received e-mail, which has been
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.
Click on "Details" to dive deeper into the crypto stuff.
Not very impressive :)